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+Copyright @copyright{} 1995--2016 Free Software Foundation, Inc.
+
+@quotation
+Permission is granted to copy, distribute and/or modify this document
+under the terms of the GNU Free Documentation License, Version 1.3 or
+any later version published by the Free Software Foundation; with no
+Invariant Sections, with the Front-Cover Texts being ``A GNU Manual'',
+and with the Back-Cover Texts as in (a) below. A copy of the license
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+
+(a) The FSF's Back-Cover Text is: ``You have the freedom to copy and
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+\gnusauthor{by Lars Magne Ingebrigtsen}
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+@end iftex
+
+@dircategory Emacs network features
+@direntry
+* Gnus: (gnus). The newsreader Gnus.
+@end direntry
+@iftex
+@finalout
+@end iftex
+
+
+@titlepage
+@ifset WEBHACKDEVEL
+@title Gnus Manual (DEVELOPMENT VERSION)
+@end ifset
+@ifclear WEBHACKDEVEL
+@title Gnus Manual
+@end ifclear
+
+@author by Lars Magne Ingebrigtsen
+@page
+@vskip 0pt plus 1filll
+@insertcopying
+@end titlepage
+
+@summarycontents
+@contents
+
+@node Top
+@top The Gnus Newsreader
+
+@ifinfo
+
+You can read news (and mail) from within Emacs by using Gnus. The news
+can be gotten by any nefarious means you can think of---@acronym{NNTP}, local
+spool or your mbox file. All at the same time, if you want to push your
+luck.
+
+@c Adjust ../Makefile.in if you change the following line:
+This manual corresponds to Ma Gnus v0.14
+
+@ifnottex
+@insertcopying
+@end ifnottex
+
+@end ifinfo
+
+@iftex
+
+@iflatex
+\tableofcontents
+\gnuscleardoublepage
+@end iflatex
+
+Gnus is the advanced, self-documenting, customizable, extensible
+unreal-time newsreader for GNU Emacs.
+
+Oops. That sounds oddly familiar, so let's start over again to avoid
+being accused of plagiarism:
+
+Gnus is a message-reading laboratory. It will let you look at just
+about anything as if it were a newsgroup. You can read mail with it,
+you can browse directories with it, you can @code{ftp} with it---you
+can even read news with it!
+
+Gnus tries to empower people who read news the same way Emacs empowers
+people who edit text. Gnus sets no limits to what the user should be
+allowed to do. Users are encouraged to extend Gnus to make it behave
+like they want it to behave. A program should not control people;
+people should be empowered to do what they want by using (or abusing)
+the program.
+
+@c Adjust ../Makefile.in if you change the following line:
+This manual corresponds to Ma Gnus v0.14
+
+@heading Other related manuals
+@itemize
+@item Message manual: Composing messages
+@item Emacs-MIME: Composing messages; @acronym{MIME}-specific parts.
+@item Sieve: Managing Sieve scripts in Emacs.
+@item EasyPG: @acronym{PGP/MIME} with Gnus.
+@item SASL: @acronym{SASL} authentication in Emacs.
+@end itemize
+
+@end iftex
+
+@menu
+* Starting Up:: Finding news can be a pain.
+* Group Buffer:: Selecting, subscribing and killing groups.
+* Summary Buffer:: Reading, saving and posting articles.
+* Article Buffer:: Displaying and handling articles.
+* Composing Messages:: Information on sending mail and news.
+* Select Methods:: Gnus reads all messages from various select methods.
+* Scoring:: Assigning values to articles.
+* Searching:: Mail and News search engines.
+* Various:: General purpose settings.
+* The End:: Farewell and goodbye.
+* Appendices:: Terminology, Emacs intro, @acronym{FAQ}, History, Internals.
+* GNU Free Documentation License:: The license for this documentation.
+* Index:: Variable, function and concept index.
+* Key Index:: Key Index.
+
+@c Doesn't work right in html.
+@c FIXME Do this in a more standard way.
+@ifinfo
+Other related manuals
+
+* Message:(message). Composing messages.
+* Emacs-MIME:(emacs-mime). Composing messages; @acronym{MIME}-specific parts.
+* Sieve:(sieve). Managing Sieve scripts in Emacs.
+* EasyPG:(epa). @acronym{PGP/MIME} with Gnus.
+* SASL:(sasl). @acronym{SASL} authentication in Emacs.
+@end ifinfo
+
+@detailmenu
+ --- The Detailed Node Listing ---
+
+Starting Gnus
+
+* Finding the News:: Choosing a method for getting news.
+* The Server is Down:: How can I read my mail then?
+* Slave Gnusae:: You can have more than one Gnus active at a time.
+* Fetching a Group:: Starting Gnus just to read a group.
+* New Groups:: What is Gnus supposed to do with new groups?
+* Changing Servers:: You may want to move from one server to another.
+* Startup Files:: Those pesky startup files---@file{.newsrc}.
+* Auto Save:: Recovering from a crash.
+* The Active File:: Reading the active file over a slow line Takes Time.
+* Startup Variables:: Other variables you might change.
+
+New Groups
+
+* Checking New Groups:: Determining what groups are new.
+* Subscription Methods:: What Gnus should do with new groups.
+* Filtering New Groups:: Making Gnus ignore certain new groups.
+
+Group Buffer
+
+* Group Buffer Format:: Information listed and how you can change it.
+* Group Maneuvering:: Commands for moving in the group buffer.
+* Selecting a Group:: Actually reading news.
+* Subscription Commands:: Unsubscribing, killing, subscribing.
+* Group Data:: Changing the info for a group.
+* Group Levels:: Levels? What are those, then?
+* Group Score:: A mechanism for finding out what groups you like.
+* Marking Groups:: You can mark groups for later processing.
+* Foreign Groups:: Creating and editing groups.
+* Group Parameters:: Each group may have different parameters set.
+* Listing Groups:: Gnus can list various subsets of the groups.
+* Sorting Groups:: Re-arrange the group order.
+* Group Maintenance:: Maintaining a tidy @file{.newsrc} file.
+* Browse Foreign Server:: You can browse a server. See what it has to offer.
+* Exiting Gnus:: Stop reading news and get some work done.
+* Group Topics:: A folding group mode divided into topics.
+* Non-ASCII Group Names:: Accessing groups of non-English names.
+* Misc Group Stuff:: Other stuff that you can to do.
+
+Group Buffer Format
+
+* Group Line Specification:: Deciding how the group buffer is to look.
+* Group Mode Line Specification:: The group buffer mode line.
+* Group Highlighting:: Having nice colors in the group buffer.
+
+Group Topics
+
+* Topic Commands:: Interactive E-Z commands.
+* Topic Variables:: How to customize the topics the Lisp Way.
+* Topic Sorting:: Sorting each topic individually.
+* Topic Topology:: A map of the world.
+* Topic Parameters:: Parameters that apply to all groups in a topic.
+
+Misc Group Stuff
+
+* Scanning New Messages:: Asking Gnus to see whether new messages have arrived.
+* Group Information:: Information and help on groups and Gnus.
+* Group Timestamp:: Making Gnus keep track of when you last read a group.
+* File Commands:: Reading and writing the Gnus files.
+* Sieve Commands:: Managing Sieve scripts.
+
+Summary Buffer
+
+* Summary Buffer Format:: Deciding how the summary buffer is to look.
+* Summary Maneuvering:: Moving around the summary buffer.
+* Choosing Articles:: Reading articles.
+* Paging the Article:: Scrolling the current article.
+* Reply Followup and Post:: Posting articles.
+* Delayed Articles:: Send articles at a later time.
+* Marking Articles:: Marking articles as read, expirable, etc.
+* Limiting:: You can limit the summary buffer.
+* Threading:: How threads are made.
+* Sorting the Summary Buffer:: How articles and threads are sorted.
+* Asynchronous Fetching:: Gnus might be able to pre-fetch articles.
+* Article Caching:: You may store articles in a cache.
+* Persistent Articles:: Making articles expiry-resistant.
+* Sticky Articles:: Article buffers that are not reused.
+* Article Backlog:: Having already read articles hang around.
+* Saving Articles:: Ways of customizing article saving.
+* Decoding Articles:: Gnus can treat series of (uu)encoded articles.
+* Article Treatment:: The article buffer can be mangled at will.
+* MIME Commands:: Doing MIMEy things with the articles.
+* Charsets:: Character set issues.
+* Article Commands:: Doing various things with the article buffer.
+* Summary Sorting:: Sorting the summary buffer in various ways.
+* Finding the Parent:: No child support? Get the parent.
+* Alternative Approaches:: Reading using non-default summaries.
+* Tree Display:: A more visual display of threads.
+* Mail Group Commands:: Some commands can only be used in mail groups.
+* Various Summary Stuff:: What didn't fit anywhere else.
+* Exiting the Summary Buffer:: Returning to the Group buffer,
+ or reselecting the current group.
+* Crosspost Handling:: How crossposted articles are dealt with.
+* Duplicate Suppression:: An alternative when crosspost handling fails.
+* Security:: Decrypt and Verify.
+* Mailing List:: Mailing list minor mode.
+
+Summary Buffer Format
+
+* Summary Buffer Lines:: You can specify how summary lines should look.
+* To From Newsgroups:: How to not display your own name.
+* Summary Buffer Mode Line:: You can say how the mode line should look.
+* Summary Highlighting:: Making the summary buffer all pretty and nice.
+
+Choosing Articles
+
+* Choosing Commands:: Commands for choosing articles.
+* Choosing Variables:: Variables that influence these commands.
+
+Reply, Followup and Post
+
+* Summary Mail Commands:: Sending mail.
+* Summary Post Commands:: Sending news.
+* Summary Message Commands:: Other Message-related commands.
+* Canceling and Superseding::
+
+Marking Articles
+
+* Unread Articles:: Marks for unread articles.
+* Read Articles:: Marks for read articles.
+* Other Marks:: Marks that do not affect readedness.
+* Setting Marks:: How to set and remove marks.
+* Generic Marking Commands:: How to customize the marking.
+* Setting Process Marks:: How to mark articles for later processing.
+
+Threading
+
+* Customizing Threading:: Variables you can change to affect the threading.
+* Thread Commands:: Thread based commands in the summary buffer.
+
+Customizing Threading
+
+* Loose Threads:: How Gnus gathers loose threads into bigger threads.
+* Filling In Threads:: Making the threads displayed look fuller.
+* More Threading:: Even more variables for fiddling with threads.
+* Low-Level Threading:: You thought it was over@dots{} but you were wrong!
+
+Decoding Articles
+
+* Uuencoded Articles:: Uudecode articles.
+* Shell Archives:: Unshar articles.
+* PostScript Files:: Split PostScript.
+* Other Files:: Plain save and binhex.
+* Decoding Variables:: Variables for a happy decoding.
+* Viewing Files:: You want to look at the result of the decoding?
+
+Decoding Variables
+
+* Rule Variables:: Variables that say how a file is to be viewed.
+* Other Decode Variables:: Other decode variables.
+* Uuencoding and Posting:: Variables for customizing uuencoding.
+
+Article Treatment
+
+* Article Highlighting:: You want to make the article look like fruit salad.
+* Article Fontisizing:: Making emphasized text look nice.
+* Article Hiding:: You also want to make certain info go away.
+* Article Washing:: Lots of way-neat functions to make life better.
+* Article Header:: Doing various header transformations.
+* Article Buttons:: Click on URLs, Message-IDs, addresses and the like.
+* Article Button Levels:: Controlling appearance of buttons.
+* Article Date:: Grumble, UT!
+* Article Display:: Display various stuff---X-Face, Picons, Smileys, Gravatars
+* Article Signature:: What is a signature?
+* Article Miscellanea:: Various other stuff.
+
+Alternative Approaches
+
+* Pick and Read:: First mark articles and then read them.
+* Binary Groups:: Auto-decode all articles.
+
+Various Summary Stuff
+
+* Summary Group Information:: Information oriented commands.
+* Searching for Articles:: Multiple article commands.
+* Summary Generation Commands::
+* Really Various Summary Commands:: Those pesky non-conformant commands.
+
+Article Buffer
+
+* Hiding Headers:: Deciding what headers should be displayed.
+* Using MIME:: Pushing articles through @acronym{MIME} before reading them.
+* HTML:: Reading @acronym{HTML} messages.
+* Customizing Articles:: Tailoring the look of the articles.
+* Article Keymap:: Keystrokes available in the article buffer.
+* Misc Article:: Other stuff.
+
+Composing Messages
+
+* Mail:: Mailing and replying.
+* Posting Server:: What server should you post and mail via?
+* POP before SMTP:: You cannot send a mail unless you read a mail.
+* Mail and Post:: Mailing and posting at the same time.
+* Archived Messages:: Where Gnus stores the messages you've sent.
+* Posting Styles:: An easier way to specify who you are.
+* Drafts:: Postponing messages and rejected messages.
+* Rejected Articles:: What happens if the server doesn't like your article?
+* Signing and encrypting:: How to compose secure messages.
+
+Select Methods
+
+* Server Buffer:: Making and editing virtual servers.
+* Getting News:: Reading USENET news with Gnus.
+* Using IMAP:: Reading mail from @acronym{IMAP}.
+* Getting Mail:: Reading your personal mail with Gnus.
+* Browsing the Web:: Getting messages from a plethora of Web sources.
+* Other Sources:: Reading directories, files.
+* Combined Groups:: Combining groups into one group.
+* Email Based Diary:: Using mails to manage diary events in Gnus.
+* Gnus Unplugged:: Reading news and mail offline.
+
+Server Buffer
+
+* Server Buffer Format:: You can customize the look of this buffer.
+* Server Commands:: Commands to manipulate servers.
+* Example Methods:: Examples server specifications.
+* Creating a Virtual Server:: An example session.
+* Server Variables:: Which variables to set.
+* Servers and Methods:: You can use server names as select methods.
+* Unavailable Servers:: Some servers you try to contact may be down.
+
+Getting News
+
+* NNTP:: Reading news from an @acronym{NNTP} server.
+* News Spool:: Reading news from the local spool.
+
+@acronym{NNTP}
+
+* Direct Functions:: Connecting directly to the server.
+* Indirect Functions:: Connecting indirectly to the server.
+* Common Variables:: Understood by several connection functions.
+
+Getting Mail
+
+* Mail in a Newsreader:: Important introductory notes.
+* Getting Started Reading Mail:: A simple cookbook example.
+* Splitting Mail:: How to create mail groups.
+* Mail Sources:: How to tell Gnus where to get mail from.
+* Mail Back End Variables:: Variables for customizing mail handling.
+* Fancy Mail Splitting:: Gnus can do hairy splitting of incoming mail.
+* Group Mail Splitting:: Use group customize to drive mail splitting.
+* Incorporating Old Mail:: What about the old mail you have?
+* Expiring Mail:: Getting rid of unwanted mail.
+* Washing Mail:: Removing cruft from the mail you get.
+* Duplicates:: Dealing with duplicated mail.
+* Not Reading Mail:: Using mail back ends for reading other files.
+* Choosing a Mail Back End:: Gnus can read a variety of mail formats.
+
+Mail Sources
+
+* Mail Source Specifiers:: How to specify what a mail source is.
+* Mail Source Customization:: Some variables that influence things.
+* Fetching Mail:: Using the mail source specifiers.
+
+Choosing a Mail Back End
+
+* Unix Mail Box:: Using the (quite) standard Un*x mbox.
+* Babyl:: Babyl was used by older versions of Rmail.
+* Mail Spool:: Store your mail in a private spool?
+* MH Spool:: An mhspool-like back end.
+* Maildir:: Another one-file-per-message format.
+* Mail Folders:: Having one file for each group.
+* Comparing Mail Back Ends:: An in-depth looks at pros and cons.
+
+Browsing the Web
+
+* Archiving Mail::
+* Web Searches:: Creating groups from articles that match a string.
+* RSS:: Reading RDF site summary.
+
+Other Sources
+
+* Directory Groups:: You can read a directory as if it was a newsgroup.
+* Anything Groups:: Dired? Who needs dired?
+* Document Groups:: Single files can be the basis of a group.
+* Mail-To-News Gateways:: Posting articles via mail-to-news gateways.
+* The Empty Backend:: The backend that never has any news.
+
+Document Groups
+
+* Document Server Internals:: How to add your own document types.
+
+Combined Groups
+
+* Virtual Groups:: Combining articles from many groups.
+
+Email Based Diary
+
+* The NNDiary Back End:: Basic setup and usage.
+* The Gnus Diary Library:: Utility toolkit on top of nndiary.
+* Sending or Not Sending:: A final note on sending diary messages.
+
+The NNDiary Back End
+
+* Diary Messages:: What makes a message valid for nndiary.
+* Running NNDiary:: NNDiary has two modes of operation.
+* Customizing NNDiary:: Bells and whistles.
+
+The Gnus Diary Library
+
+* Diary Summary Line Format:: A nicer summary buffer line format.
+* Diary Articles Sorting:: A nicer way to sort messages.
+* Diary Headers Generation:: Not doing it manually.
+* Diary Group Parameters:: Not handling them manually.
+
+Gnus Unplugged
+
+* Agent Basics:: How it all is supposed to work.
+* Agent Categories:: How to tell the Gnus Agent what to download.
+* Agent Commands:: New commands for all the buffers.
+* Agent Visuals:: Ways that the agent may effect your summary buffer.
+* Agent as Cache:: The Agent is a big cache too.
+* Agent Expiry:: How to make old articles go away.
+* Agent Regeneration:: How to recover from lost connections and other accidents.
+* Agent and flags:: How the Agent maintains flags.
+* Agent and IMAP:: How to use the Agent with @acronym{IMAP}.
+* Outgoing Messages:: What happens when you post/mail something?
+* Agent Variables:: Customizing is fun.
+* Example Setup:: An example @file{~/.gnus.el} file for offline people.
+* Batching Agents:: How to fetch news from a @code{cron} job.
+* Agent Caveats:: What you think it'll do and what it does.
+
+Agent Categories
+
+* Category Syntax:: What a category looks like.
+* Category Buffer:: A buffer for maintaining categories.
+* Category Variables:: Customize'r'Us.
+
+Agent Commands
+
+* Group Agent Commands:: Configure groups and fetch their contents.
+* Summary Agent Commands:: Manually select then fetch specific articles.
+* Server Agent Commands:: Select the servers that are supported by the agent.
+
+Scoring
+
+* Summary Score Commands:: Adding score entries for the current group.
+* Group Score Commands:: General score commands.
+* Score Variables:: Customize your scoring. (My, what terminology).
+* Score File Format:: What a score file may contain.
+* Score File Editing:: You can edit score files by hand as well.
+* Adaptive Scoring:: Big Sister Gnus knows what you read.
+* Home Score File:: How to say where new score entries are to go.
+* Followups To Yourself:: Having Gnus notice when people answer you.
+* Scoring On Other Headers:: Scoring on non-standard headers.
+* Scoring Tips:: How to score effectively.
+* Reverse Scoring:: That problem child of old is not problem.
+* Global Score Files:: Earth-spanning, ear-splitting score files.
+* Kill Files:: They are still here, but they can be ignored.
+* Converting Kill Files:: Translating kill files to score files.
+* Advanced Scoring:: Using logical expressions to build score rules.
+* Score Decays:: It can be useful to let scores wither away.
+
+Advanced Scoring
+
+* Advanced Scoring Syntax:: A definition.
+* Advanced Scoring Examples:: What they look like.
+* Advanced Scoring Tips:: Getting the most out of it.
+
+Searching
+
+* nnir:: Searching with various engines.
+* nnmairix:: Searching with Mairix.
+
+nnir
+
+* What is nnir?:: What does nnir do.
+* Basic Usage:: How to perform simple searches.
+* Setting up nnir:: How to set up nnir.
+
+Setting up nnir
+
+* Associating Engines:: How to associate engines.
+
+Various
+
+* Process/Prefix:: A convention used by many treatment commands.
+* Interactive:: Making Gnus ask you many questions.
+* Symbolic Prefixes:: How to supply some Gnus functions with options.
+* Formatting Variables:: You can specify what buffers should look like.
+* Window Layout:: Configuring the Gnus buffer windows.
+* Faces and Fonts:: How to change how faces look.
+* Mode Lines:: Displaying information in the mode lines.
+* Highlighting and Menus:: Making buffers look all nice and cozy.
+* Daemons:: Gnus can do things behind your back.
+* Undo:: Some actions can be undone.
+* Predicate Specifiers:: Specifying predicates.
+* Moderation:: What to do if you're a moderator.
+* Image Enhancements:: Modern versions of Emacs/XEmacs can display images.
+* Fuzzy Matching:: What's the big fuzz?
+* Thwarting Email Spam:: Simple ways to avoid unsolicited commercial email.
+* Spam Package:: A package for filtering and processing spam.
+* The Gnus Registry:: A package for tracking messages by Message-ID.
+* Other modes:: Interaction with other modes.
+* Various Various:: Things that are really various.
+
+Formatting Variables
+
+* Formatting Basics:: A formatting variable is basically a format string.
+* Mode Line Formatting:: Some rules about mode line formatting variables.
+* Advanced Formatting:: Modifying output in various ways.
+* User-Defined Specs:: Having Gnus call your own functions.
+* Formatting Fonts:: Making the formatting look colorful and nice.
+* Positioning Point:: Moving point to a position after an operation.
+* Tabulation:: Tabulating your output.
+* Wide Characters:: Dealing with wide characters.
+
+Image Enhancements
+
+* X-Face:: Display a funky, teensy black-and-white image.
+* Face:: Display a funkier, teensier colored image.
+* Smileys:: Show all those happy faces the way they were
+ meant to be shown.
+* Picons:: How to display pictures of what you're reading.
+* Gravatars:: Display the avatar of people you read.
+* XVarious:: Other XEmacsy Gnusey variables.
+
+Thwarting Email Spam
+
+* The problem of spam:: Some background, and some solutions
+* Anti-Spam Basics:: Simple steps to reduce the amount of spam.
+* SpamAssassin:: How to use external anti-spam tools.
+* Hashcash:: Reduce spam by burning CPU time.
+
+Spam Package
+
+* Spam Package Introduction::
+* Filtering Incoming Mail::
+* Detecting Spam in Groups::
+* Spam and Ham Processors::
+* Spam Package Configuration Examples::
+* Spam Back Ends::
+* Extending the Spam package::
+* Spam Statistics Package::
+
+Spam Statistics Package
+
+* Creating a spam-stat dictionary::
+* Splitting mail using spam-stat::
+* Low-level interface to the spam-stat dictionary::
+
+Appendices
+
+* XEmacs:: Requirements for installing under XEmacs.
+* History:: How Gnus got where it is today.
+* On Writing Manuals:: Why this is not a beginner's guide.
+* Terminology:: We use really difficult, like, words here.
+* Customization:: Tailoring Gnus to your needs.
+* Troubleshooting:: What you might try if things do not work.
+* Gnus Reference Guide:: Rilly, rilly technical stuff.
+* Emacs for Heathens:: A short introduction to Emacsian terms.
+* Frequently Asked Questions:: The Gnus FAQ
+
+History
+
+* Gnus Versions:: What Gnus versions have been released.
+* Why?:: What's the point of Gnus?
+* Compatibility:: Just how compatible is Gnus with @sc{gnus}?
+* Conformity:: Gnus tries to conform to all standards.
+* Emacsen:: Gnus can be run on a few modern Emacsen.
+* Gnus Development:: How Gnus is developed.
+* Contributors:: Oodles of people.
+* New Features:: Pointers to some of the new stuff in Gnus.
+
+New Features
+
+* ding Gnus:: New things in Gnus 5.0/5.1, the first new Gnus.
+* September Gnus:: The Thing Formally Known As Gnus 5.2/5.3.
+* Red Gnus:: Third time best---Gnus 5.4/5.5.
+* Quassia Gnus:: Two times two is four, or Gnus 5.6/5.7.
+* Pterodactyl Gnus:: Pentad also starts with P, AKA Gnus 5.8/5.9.
+* Oort Gnus:: It's big. It's far out. Gnus 5.10/5.11.
+* No Gnus:: Very punny. Gnus 5.12/5.13
+* Ma Gnus:: Celebrating 25 years of Gnus.
+
+Customization
+
+* Slow/Expensive Connection:: You run a local Emacs and get the news elsewhere.
+* Slow Terminal Connection:: You run a remote Emacs.
+* Little Disk Space:: You feel that having large setup files is icky.
+* Slow Machine:: You feel like buying a faster machine.
+
+Gnus Reference Guide
+
+* Gnus Utility Functions:: Common functions and variable to use.
+* Back End Interface:: How Gnus communicates with the servers.
+* Score File Syntax:: A BNF definition of the score file standard.
+* Headers:: How Gnus stores headers internally.
+* Ranges:: A handy format for storing mucho numbers.
+* Group Info:: The group info format.
+* Extended Interactive:: Symbolic prefixes and stuff.
+* Emacs/XEmacs Code:: Gnus can be run under all modern Emacsen.
+* Various File Formats:: Formats of files that Gnus use.
+
+Back End Interface
+
+* Required Back End Functions:: Functions that must be implemented.
+* Optional Back End Functions:: Functions that need not be implemented.
+* Error Messaging:: How to get messages and report errors.
+* Writing New Back Ends:: Extending old back ends.
+* Hooking New Back Ends Into Gnus:: What has to be done on the Gnus end.
+* Mail-like Back Ends:: Some tips on mail back ends.
+
+Various File Formats
+
+* Active File Format:: Information on articles and groups available.
+* Newsgroups File Format:: Group descriptions.
+
+Emacs for Heathens
+
+* Keystrokes:: Entering text and executing commands.
+* Emacs Lisp:: The built-in Emacs programming language.
+
+@end detailmenu
+@end menu
+
+@node Starting Up
+@chapter Starting Gnus
+@cindex starting up
+
+If you haven't used Emacs much before using Gnus, read @ref{Emacs for
+Heathens} first.
+
+@kindex M-x gnus
+@findex gnus
+If your system administrator has set things up properly, starting Gnus
+and reading news is extremely easy---you just type @kbd{M-x gnus} in
+your Emacs. If not, you should customize the variable
+@code{gnus-select-method} as described in @ref{Finding the News}. For a
+minimal setup for posting should also customize the variables
+@code{user-full-name} and @code{user-mail-address}.
+
+@findex gnus-other-frame
+@kindex M-x gnus-other-frame
+If you want to start Gnus in a different frame, you can use the command
+@kbd{M-x gnus-other-frame} instead.
+
+If things do not go smoothly at startup, you have to twiddle some
+variables in your @file{~/.gnus.el} file. This file is similar to
+@file{~/.emacs}, but is read when Gnus starts.
+
+If you puzzle at any terms used in this manual, please refer to the
+terminology section (@pxref{Terminology}).
+
+@menu
+* Finding the News:: Choosing a method for getting news.
+* The Server is Down:: How can I read my mail then?
+* Slave Gnusae:: You can have more than one Gnus active at a time.
+* New Groups:: What is Gnus supposed to do with new groups?
+* Changing Servers:: You may want to move from one server to another.
+* Startup Files:: Those pesky startup files---@file{.newsrc}.
+* Auto Save:: Recovering from a crash.
+* The Active File:: Reading the active file over a slow line Takes Time.
+* Startup Variables:: Other variables you might change.
+@end menu
+
+
+@node Finding the News
+@section Finding the News
+@cindex finding news
+
+First of all, you should know that there is a special buffer called
+@file{*Server*} that lists all the servers Gnus knows about. You can
+press @kbd{^} from the Group buffer to see it. In the Server buffer,
+you can press @kbd{RET} on a defined server to see all the groups it
+serves (subscribed or not!). You can also add or delete servers, edit
+a foreign server's definition, agentize or de-agentize a server, and
+do many other neat things. @xref{Server Buffer}.
+@xref{Foreign Groups}. @xref{Agent Basics}.
+
+@vindex gnus-select-method
+@c @head
+The @code{gnus-select-method} variable says where Gnus should look for
+news. This variable should be a list where the first element says
+@dfn{how} and the second element says @dfn{where}. This method is your
+native method. All groups not fetched with this method are
+secondary or foreign groups.
+
+For instance, if the @samp{news.somewhere.edu} @acronym{NNTP} server is where
+you want to get your daily dosage of news from, you'd say:
+
+@lisp
+(setq gnus-select-method '(nntp "news.somewhere.edu"))
+@end lisp
+
+If you want to read directly from the local spool, say:
+
+@lisp
+(setq gnus-select-method '(nnspool ""))
+@end lisp
+
+If you can use a local spool, you probably should, as it will almost
+certainly be much faster. But do not use the local spool if your
+server is running Leafnode (which is a simple, standalone private news
+server); in this case, use @code{(nntp "localhost")}.
+
+@vindex gnus-nntpserver-file
+@cindex NNTPSERVER
+@cindex @acronym{NNTP} server
+If this variable is not set, Gnus will take a look at the
+@env{NNTPSERVER} environment variable. If that variable isn't set,
+Gnus will see whether @code{gnus-nntpserver-file}
+(@file{/etc/nntpserver} by default) has any opinions on the matter.
+If that fails as well, Gnus will try to use the machine running Emacs
+as an @acronym{NNTP} server. That's a long shot, though.
+
+@findex gnus-group-browse-foreign-server
+@kindex B (Group)
+However, if you use one @acronym{NNTP} server regularly and are just
+interested in a couple of groups from a different server, you would be
+better served by using the @kbd{B} command in the group buffer. It will
+let you have a look at what groups are available, and you can subscribe
+to any of the groups you want to. This also makes @file{.newsrc}
+maintenance much tidier. @xref{Foreign Groups}.
+
+@vindex gnus-secondary-select-methods
+@c @head
+A slightly different approach to foreign groups is to set the
+@code{gnus-secondary-select-methods} variable. The select methods
+listed in this variable are in many ways just as native as the
+@code{gnus-select-method} server. They will also be queried for active
+files during startup (if that's required), and new newsgroups that
+appear on these servers will be subscribed (or not) just as native
+groups are.
+
+For instance, if you use the @code{nnmbox} back end to read your mail,
+you would typically set this variable to
+
+@lisp
+(setq gnus-secondary-select-methods '((nnmbox "")))
+@end lisp
+
+
+
+@node The Server is Down
+@section The Server is Down
+@cindex server errors
+
+If the default server is down, Gnus will understandably have some
+problems starting. However, if you have some mail groups in addition to
+the news groups, you may want to start Gnus anyway.
+
+Gnus, being the trusting sort of program, will ask whether to proceed
+without a native select method if that server can't be contacted. This
+will happen whether the server doesn't actually exist (i.e., you have
+given the wrong address) or the server has just momentarily taken ill
+for some reason or other. If you decide to continue and have no foreign
+groups, you'll find it difficult to actually do anything in the group
+buffer. But, hey, that's your problem. Blllrph!
+
+@findex gnus-no-server
+@kindex M-x gnus-no-server
+@c @head
+If you know that the server is definitely down, or you just want to read
+your mail without bothering with the server at all, you can use the
+@code{gnus-no-server} command to start Gnus. That might come in handy
+if you're in a hurry as well. This command will not attempt to contact
+your primary server---instead, it will just activate all groups on level
+1 and 2. (You should preferably keep no native groups on those two
+levels.) Also @pxref{Group Levels}.
+
+
+@node Slave Gnusae
+@section Slave Gnusae
+@cindex slave
+
+You might want to run more than one Emacs with more than one Gnus at the
+same time. If you are using different @file{.newsrc} files (e.g., if you
+are using the two different Gnusae to read from two different servers),
+that is no problem whatsoever. You just do it.
+
+The problem appears when you want to run two Gnusae that use the same
+@file{.newsrc} file.
+
+To work around that problem some, we here at the Think-Tank at the Gnus
+Towers have come up with a new concept: @dfn{Masters} and
+@dfn{slaves}. (We have applied for a patent on this concept, and have
+taken out a copyright on those words. If you wish to use those words in
+conjunction with each other, you have to send $1 per usage instance to
+me. Usage of the patent (@dfn{Master/Slave Relationships In Computer
+Applications}) will be much more expensive, of course.)
+
+@findex gnus-slave
+Anyway, you start one Gnus up the normal way with @kbd{M-x gnus} (or
+however you do it). Each subsequent slave Gnusae should be started with
+@kbd{M-x gnus-slave}. These slaves won't save normal @file{.newsrc}
+files, but instead save @dfn{slave files} that contain information only
+on what groups have been read in the slave session. When a master Gnus
+starts, it will read (and delete) these slave files, incorporating all
+information from them. (The slave files will be read in the sequence
+they were created, so the latest changes will have precedence.)
+
+Information from the slave files has, of course, precedence over the
+information in the normal (i.e., master) @file{.newsrc} file.
+
+If the @file{.newsrc*} files have not been saved in the master when the
+slave starts, you may be prompted as to whether to read an auto-save
+file. If you answer ``yes'', the unsaved changes to the master will be
+incorporated into the slave. If you answer ``no'', the slave may see some
+messages as unread that have been read in the master.
+
+
+
+@node New Groups
+@section New Groups
+@cindex new groups
+@cindex subscription
+
+@vindex gnus-check-new-newsgroups
+If you are satisfied that you really never want to see any new groups,
+you can set @code{gnus-check-new-newsgroups} to @code{nil}. This will
+also save you some time at startup. Even if this variable is
+@code{nil}, you can always subscribe to the new groups just by pressing
+@kbd{U} in the group buffer (@pxref{Group Maintenance}). This variable
+is @code{ask-server} by default. If you set this variable to
+@code{always}, then Gnus will query the back ends for new groups even
+when you do the @kbd{g} command (@pxref{Scanning New Messages}).
+
+@menu
+* Checking New Groups:: Determining what groups are new.
+* Subscription Methods:: What Gnus should do with new groups.
+* Filtering New Groups:: Making Gnus ignore certain new groups.
+@end menu
+
+
+@node Checking New Groups
+@subsection Checking New Groups
+
+Gnus normally determines whether a group is new or not by comparing
+the list of groups from the active file(s) with the lists of
+subscribed and dead groups. This isn't a particularly fast method.
+If @code{gnus-check-new-newsgroups} is @code{ask-server}, Gnus will
+ask the server for new groups since the last time. This is both
+faster and cheaper. This also means that you can get rid of the list
+of killed groups (@pxref{Group Levels}) altogether, so you may set
+@code{gnus-save-killed-list} to @code{nil}, which will save time both
+at startup, at exit, and all over. Saves disk space, too. Why isn't
+this the default, then? Unfortunately, not all servers support this
+command.
+
+I bet I know what you're thinking now: How do I find out whether my
+server supports @code{ask-server}? No? Good, because I don't have a
+fail-safe answer. I would suggest just setting this variable to
+@code{ask-server} and see whether any new groups appear within the next
+few days. If any do, then it works. If none do, then it doesn't
+work. I could write a function to make Gnus guess whether the server
+supports @code{ask-server}, but it would just be a guess. So I won't.
+You could @code{telnet} to the server and say @code{HELP} and see
+whether it lists @samp{NEWGROUPS} among the commands it understands. If
+it does, then it might work. (But there are servers that lists
+@samp{NEWGROUPS} without supporting the function properly.)
+
+This variable can also be a list of select methods. If so, Gnus will
+issue an @code{ask-server} command to each of the select methods, and
+subscribe them (or not) using the normal methods. This might be handy
+if you are monitoring a few servers for new groups. A side effect is
+that startup will take much longer, so you can meditate while waiting.
+Use the mantra ``dingnusdingnusdingnus'' to achieve permanent bliss.
+
+
+@node Subscription Methods
+@subsection Subscription Methods
+
+@vindex gnus-subscribe-newsgroup-method
+What Gnus does when it encounters a new group is determined by the
+@code{gnus-subscribe-newsgroup-method} variable.
+
+This variable should contain a function. This function will be called
+with the name of the new group as the only parameter.
+
+Some handy pre-fab functions are:
+
+@table @code
+
+@item gnus-subscribe-zombies
+@vindex gnus-subscribe-zombies
+Make all new groups zombies (@pxref{Group Levels}). This is the
+default. You can browse the zombies later (with @kbd{A z}) and either
+kill them all off properly (with @kbd{S z}), or subscribe to them
+(with @kbd{u}).
+
+@item gnus-subscribe-randomly
+@vindex gnus-subscribe-randomly
+Subscribe all new groups in arbitrary order. This really means that all
+new groups will be added at ``the top'' of the group buffer.
+
+@item gnus-subscribe-alphabetically
+@vindex gnus-subscribe-alphabetically
+Subscribe all new groups in alphabetical order.
+
+@item gnus-subscribe-hierarchically
+@vindex gnus-subscribe-hierarchically
+Subscribe all new groups hierarchically. The difference between this
+function and @code{gnus-subscribe-alphabetically} is slight.
+@code{gnus-subscribe-alphabetically} will subscribe new groups in a strictly
+alphabetical fashion, while this function will enter groups into its
+hierarchy. So if you want to have the @samp{rec} hierarchy before the
+@samp{comp} hierarchy, this function will not mess that configuration
+up. Or something like that.
+
+@item gnus-subscribe-interactively
+@vindex gnus-subscribe-interactively
+Subscribe new groups interactively. This means that Gnus will ask
+you about @strong{all} new groups. The groups you choose to subscribe
+to will be subscribed hierarchically.
+
+@item gnus-subscribe-killed
+@vindex gnus-subscribe-killed
+Kill all new groups.
+
+@item gnus-subscribe-topics
+@vindex gnus-subscribe-topics
+Put the groups into the topic that has a matching @code{subscribe} topic
+parameter (@pxref{Topic Parameters}). For instance, a @code{subscribe}
+topic parameter that looks like
+
+@example
+"nnml"
+@end example
+
+will mean that all groups that match that regex will be subscribed under
+that topic.
+
+If no topics match the groups, the groups will be subscribed in the
+top-level topic.
+
+@end table
+
+@vindex gnus-subscribe-hierarchical-interactive
+A closely related variable is
+@code{gnus-subscribe-hierarchical-interactive}. (That's quite a
+mouthful.) If this variable is non-@code{nil}, Gnus will ask you in a
+hierarchical fashion whether to subscribe to new groups or not. Gnus
+will ask you for each sub-hierarchy whether you want to descend the
+hierarchy or not.
+
+One common mistake is to set the variable a few paragraphs above
+(@code{gnus-subscribe-newsgroup-method}) to
+@code{gnus-subscribe-hierarchical-interactive}. This is an error. This
+will not work. This is ga-ga. So don't do it.
+
+
+@node Filtering New Groups
+@subsection Filtering New Groups
+
+A nice and portable way to control which new newsgroups should be
+subscribed (or ignored) is to put an @dfn{options} line at the start of
+the @file{.newsrc} file. Here's an example:
+
+@example
+options -n !alt.all !rec.all sci.all
+@end example
+
+@vindex gnus-subscribe-options-newsgroup-method
+This line obviously belongs to a serious-minded intellectual scientific
+person (or she may just be plain old boring), because it says that all
+groups that have names beginning with @samp{alt} and @samp{rec} should
+be ignored, and all groups with names beginning with @samp{sci} should
+be subscribed. Gnus will not use the normal subscription method for
+subscribing these groups.
+@code{gnus-subscribe-options-newsgroup-method} is used instead. This
+variable defaults to @code{gnus-subscribe-alphabetically}.
+
+The ``options -n'' format is very simplistic. The syntax above is all
+that is supports: you can force-subscribe hierarchies, or you can
+deny hierarchies, and that's it.
+
+@vindex gnus-options-not-subscribe
+@vindex gnus-options-subscribe
+If you don't want to mess with your @file{.newsrc} file, you can just
+set the two variables @code{gnus-options-subscribe} and
+@code{gnus-options-not-subscribe}. These two variables do exactly the
+same as the @file{.newsrc} @samp{options -n} trick. Both are regexps,
+and if the new group matches the former, it will be unconditionally
+subscribed, and if it matches the latter, it will be ignored.
+
+@vindex gnus-auto-subscribed-groups
+Yet another variable that meddles here is
+@code{gnus-auto-subscribed-groups}. It works exactly like
+@code{gnus-options-subscribe}, and is therefore really superfluous,
+but I thought it would be nice to have two of these. This variable is
+more meant for setting some ground rules, while the other variable is
+used more for user fiddling. By default this variable makes all new
+groups that come from mail back ends (@code{nnml}, @code{nnbabyl},
+@code{nnfolder}, @code{nnmbox}, @code{nnmh}, @code{nnimap}, and
+@code{nnmaildir}) subscribed. If you don't like that, just set this
+variable to @code{nil}.
+
+@vindex gnus-auto-subscribed-categories
+As if that wasn't enough, @code{gnus-auto-subscribed-categories} also
+allows you to specify that new groups should be subscribed based on the
+category their select methods belong to. The default is @samp{(mail
+post-mail)}, meaning that all new groups from mail-like backends
+should be subscribed automatically.
+
+New groups that match these variables are subscribed using
+@code{gnus-subscribe-options-newsgroup-method}.
+
+
+@node Changing Servers
+@section Changing Servers
+@cindex changing servers
+
+Sometimes it is necessary to move from one @acronym{NNTP} server to another.
+This happens very rarely, but perhaps you change jobs, or one server is
+very flaky and you want to use another.
+
+Changing the server is pretty easy, right? You just change
+@code{gnus-select-method} to point to the new server?
+
+@emph{Wrong!}
+
+Article numbers are not (in any way) kept synchronized between different
+@acronym{NNTP} servers, and the only way Gnus keeps track of what articles
+you have read is by keeping track of article numbers. So when you
+change @code{gnus-select-method}, your @file{.newsrc} file becomes
+worthless.
+
+@kindex M-x gnus-group-clear-data-on-native-groups
+@findex gnus-group-clear-data-on-native-groups
+You can use the @kbd{M-x gnus-group-clear-data-on-native-groups}
+command to clear out all data that you have on your native groups.
+Use with caution.
+
+@kindex M-x gnus-group-clear-data
+@findex gnus-group-clear-data
+Clear the data from the current group only---nix out marks and the
+list of read articles (@code{gnus-group-clear-data}).
+
+After changing servers, you @strong{must} move the cache hierarchy away,
+since the cached articles will have wrong article numbers, which will
+affect which articles Gnus thinks are read.
+@code{gnus-group-clear-data-on-native-groups} will ask you if you want
+to have it done automatically; for @code{gnus-group-clear-data}, you
+can use @kbd{M-x gnus-cache-move-cache} (but beware, it will move the
+cache for all groups).
+
+
+@node Startup Files
+@section Startup Files
+@cindex startup files
+@cindex .newsrc
+@cindex .newsrc.el
+@cindex .newsrc.eld
+
+Most common Unix news readers use a shared startup file called
+@file{.newsrc}. This file contains all the information about what
+groups are subscribed, and which articles in these groups have been
+read.
+
+Things got a bit more complicated with @sc{gnus}. In addition to
+keeping the @file{.newsrc} file updated, it also used a file called
+@file{.newsrc.el} for storing all the information that didn't fit into
+the @file{.newsrc} file. (Actually, it also duplicated everything in
+the @file{.newsrc} file.) @sc{gnus} would read whichever one of these
+files was the most recently saved, which enabled people to swap between
+@sc{gnus} and other newsreaders.
+
+That was kinda silly, so Gnus went one better: In addition to the
+@file{.newsrc} and @file{.newsrc.el} files, Gnus also has a file called
+@file{.newsrc.eld}. It will read whichever of these files that are most
+recent, but it will never write a @file{.newsrc.el} file. You should
+never delete the @file{.newsrc.eld} file---it contains much information
+not stored in the @file{.newsrc} file.
+
+@vindex gnus-save-newsrc-file
+@vindex gnus-read-newsrc-file
+You can turn off writing the @file{.newsrc} file by setting
+@code{gnus-save-newsrc-file} to @code{nil}, which means you can delete
+the file and save some space, as well as exiting from Gnus faster.
+However, this will make it impossible to use other newsreaders than
+Gnus. But hey, who would want to, right? Similarly, setting
+@code{gnus-read-newsrc-file} to @code{nil} makes Gnus ignore the
+@file{.newsrc} file and any @file{.newsrc-SERVER} files, which can be
+convenient if you use a different news reader occasionally, and you
+want to read a different subset of the available groups with that
+news reader.
+
+@vindex gnus-save-killed-list
+If @code{gnus-save-killed-list} (default @code{t}) is @code{nil}, Gnus
+will not save the list of killed groups to the startup file. This will
+save both time (when starting and quitting) and space (on disk). It
+will also mean that Gnus has no record of what groups are new or old,
+so the automatic new groups subscription methods become meaningless.
+You should always set @code{gnus-check-new-newsgroups} to @code{nil} or
+@code{ask-server} if you set this variable to @code{nil} (@pxref{New
+Groups}). This variable can also be a regular expression. If that's
+the case, remove all groups that do not match this regexp before
+saving. This can be useful in certain obscure situations that involve
+several servers where not all servers support @code{ask-server}.
+
+@vindex gnus-startup-file
+@vindex gnus-backup-startup-file
+@vindex version-control
+The @code{gnus-startup-file} variable says where the startup files are.
+The default value is @file{~/.newsrc}, with the Gnus (El Dingo) startup
+file being whatever that one is, with a @samp{.eld} appended.
+If you want to keep multiple numbered backups of this file, set
+@code{gnus-backup-startup-file}. It respects the same values as the
+@code{version-control} variable.
+
+@vindex gnus-save-newsrc-hook
+@vindex gnus-save-quick-newsrc-hook
+@vindex gnus-save-standard-newsrc-hook
+@code{gnus-save-newsrc-hook} is called before saving any of the newsrc
+files, while @code{gnus-save-quick-newsrc-hook} is called just before
+saving the @file{.newsrc.eld} file, and
+@code{gnus-save-standard-newsrc-hook} is called just before saving the
+@file{.newsrc} file. The latter two are commonly used to turn version
+control on or off. Version control is on by default when saving the
+startup files. If you want to turn backup creation off, say something like:
+
+@lisp
+(defun turn-off-backup ()
+ (set (make-local-variable 'backup-inhibited) t))
+
+(add-hook 'gnus-save-quick-newsrc-hook 'turn-off-backup)
+(add-hook 'gnus-save-standard-newsrc-hook 'turn-off-backup)
+@end lisp
+
+@vindex gnus-init-file
+@vindex gnus-site-init-file
+When Gnus starts, it will read the @code{gnus-site-init-file}
+(@file{.../site-lisp/gnus-init} by default) and @code{gnus-init-file}
+(@file{~/.gnus} by default) files. These are normal Emacs Lisp files
+and can be used to avoid cluttering your @file{~/.emacs} and
+@file{site-init} files with Gnus stuff. Gnus will also check for files
+with the same names as these, but with @file{.elc} and @file{.el}
+suffixes. In other words, if you have set @code{gnus-init-file} to
+@file{~/.gnus}, it will look for @file{~/.gnus.elc}, @file{~/.gnus.el},
+and finally @file{~/.gnus} (in this order). If Emacs was invoked with
+the @option{-q} or @option{--no-init-file} options (@pxref{Initial
+Options, ,Initial Options, emacs, The Emacs Manual}), Gnus doesn't read
+@code{gnus-init-file}.
+
+
+@node Auto Save
+@section Auto Save
+@cindex dribble file
+@cindex auto-save
+
+Whenever you do something that changes the Gnus data (reading articles,
+catching up, killing/subscribing groups), the change is added to a
+special @dfn{dribble buffer}. This buffer is auto-saved the normal
+Emacs way. If your Emacs should crash before you have saved the
+@file{.newsrc} files, all changes you have made can be recovered from
+this file.
+
+If Gnus detects this file at startup, it will ask the user whether to
+read it. The auto save file is deleted whenever the real startup file is
+saved.
+
+@vindex gnus-use-dribble-file
+If @code{gnus-use-dribble-file} is @code{nil}, Gnus won't create and
+maintain a dribble buffer. The default is @code{t}.
+
+@vindex gnus-dribble-directory
+Gnus will put the dribble file(s) in @code{gnus-dribble-directory}. If
+this variable is @code{nil}, which it is by default, Gnus will dribble
+into the directory where the @file{.newsrc} file is located. (This is
+normally the user's home directory.) The dribble file will get the same
+file permissions as the @file{.newsrc} file.
+
+@vindex gnus-always-read-dribble-file
+If @code{gnus-always-read-dribble-file} is non-@code{nil}, Gnus will
+read the dribble file on startup without querying the user.
+
+
+@node The Active File
+@section The Active File
+@cindex active file
+@cindex ignored groups
+
+When Gnus starts, or indeed whenever it tries to determine whether new
+articles have arrived, it reads the active file. This is a very large
+file that lists all the active groups and articles on the server.
+
+@vindex gnus-ignored-newsgroups
+Before examining the active file, Gnus deletes all lines that match the
+regexp @code{gnus-ignored-newsgroups}. This is done primarily to reject
+any groups with bogus names, but you can use this variable to make Gnus
+ignore hierarchies you aren't ever interested in. However, this is not
+recommended. In fact, it's highly discouraged. Instead, @pxref{New
+Groups} for an overview of other variables that can be used instead.
+
+@c This variable is
+@c @code{nil} by default, and will slow down active file handling somewhat
+@c if you set it to anything else.
+
+@vindex gnus-read-active-file
+@c @head
+The active file can be rather Huge, so if you have a slow network, you
+can set @code{gnus-read-active-file} to @code{nil} to prevent Gnus from
+reading the active file. This variable is @code{some} by default.
+
+Gnus will try to make do by getting information just on the groups that
+you actually subscribe to.
+
+Note that if you subscribe to lots and lots of groups, setting this
+variable to @code{nil} will probably make Gnus slower, not faster. At
+present, having this variable @code{nil} will slow Gnus down
+considerably, unless you read news over a 2400 baud modem.
+
+This variable can also have the value @code{some}. Gnus will then
+attempt to read active info only on the subscribed groups. On some
+servers this is quite fast (on sparkling, brand new INN servers that
+support the @code{LIST ACTIVE group} command), on others this isn't fast
+at all. In any case, @code{some} should be faster than @code{nil}, and
+is certainly faster than @code{t} over slow lines.
+
+Some news servers (old versions of Leafnode and old versions of INN, for
+instance) do not support the @code{LIST ACTIVE group}. For these
+servers, @code{nil} is probably the most efficient value for this
+variable.
+
+If this variable is @code{nil}, Gnus will ask for group info in total
+lock-step, which isn't very fast. If it is @code{some} and you use an
+@acronym{NNTP} server, Gnus will pump out commands as fast as it can, and
+read all the replies in one swoop. This will normally result in better
+performance, but if the server does not support the aforementioned
+@code{LIST ACTIVE group} command, this isn't very nice to the server.
+
+If you think that starting up Gnus takes too long, try all the three
+different values for this variable and see what works best for you.
+
+In any case, if you use @code{some} or @code{nil}, you should definitely
+kill all groups that you aren't interested in to speed things up.
+
+Note that this variable also affects active file retrieval from
+secondary select methods.
+
+
+@node Startup Variables
+@section Startup Variables
+
+@table @code
+
+@item gnus-load-hook
+@vindex gnus-load-hook
+A hook run while Gnus is being loaded. Note that this hook will
+normally be run just once in each Emacs session, no matter how many
+times you start Gnus.
+
+@item gnus-before-startup-hook
+@vindex gnus-before-startup-hook
+A hook called as the first thing when Gnus is started.
+
+@item gnus-before-resume-hook
+@vindex gnus-before-resume-hook
+A hook called as the first thing when Gnus is resumed after a suspend.
+
+@item gnus-startup-hook
+@vindex gnus-startup-hook
+A hook run as the very last thing after starting up Gnus
+
+@item gnus-started-hook
+@vindex gnus-started-hook
+A hook that is run as the very last thing after starting up Gnus
+successfully.
+
+@item gnus-setup-news-hook
+@vindex gnus-setup-news-hook
+A hook that is run after reading the @file{.newsrc} file(s), but before
+generating the group buffer.
+
+@item gnus-check-bogus-newsgroups
+@vindex gnus-check-bogus-newsgroups
+If non-@code{nil}, Gnus will check for and delete all bogus groups at
+startup. A @dfn{bogus group} is a group that you have in your
+@file{.newsrc} file, but doesn't exist on the news server. Checking for
+bogus groups can take quite a while, so to save time and resources it's
+best to leave this option off, and do the checking for bogus groups once
+in a while from the group buffer instead (@pxref{Group Maintenance}).
+
+@item gnus-inhibit-startup-message
+@vindex gnus-inhibit-startup-message
+If non-@code{nil}, the startup message won't be displayed. That way,
+your boss might not notice as easily that you are reading news instead
+of doing your job. Note that this variable is used before
+@file{~/.gnus.el} is loaded, so it should be set in @file{.emacs} instead.
+
+@item gnus-no-groups-message
+@vindex gnus-no-groups-message
+Message displayed by Gnus when no groups are available.
+
+@item gnus-use-backend-marks
+@vindex gnus-use-backend-marks
+If non-@code{nil}, Gnus will store article marks both in the
+@file{.newsrc.eld} file and in the backends. This will slow down
+group operation some.
+
+@end table
+
+
+@node Group Buffer
+@chapter Group Buffer
+@cindex group buffer
+
+@c Alex Schroeder suggests to rearrange this as follows:
+@c
+@c <kensanata> ok, just save it for reference. I'll go to bed in a minute.
+@c 1. Selecting a Group, 2. (new) Finding a Group, 3. Group Levels,
+@c 4. Subscription Commands, 5. Group Maneuvering, 6. Group Data,
+@c 7. Group Score, 8. Group Buffer Format
+@c <kensanata> Group Levels should have more information on levels 5 to 9. I
+@c suggest to split the 4th paragraph ("Gnus considers groups...") as follows:
+@c <kensanata> First, "Gnus considers groups... (default 9)."
+@c <kensanata> New, a table summarizing what levels 1 to 9 mean.
+@c <kensanata> Third, "Gnus treats subscribed ... reasons of efficiency"
+@c <kensanata> Then expand the next paragraph or add some more to it.
+@c This short one sentence explains levels 1 and 2, therefore I understand
+@c that I should keep important news at 3 and boring news at 4.
+@c Say so! Then go on to explain why I should bother with levels 6 to 9.
+@c Maybe keep those that you don't want to read temporarily at 6,
+@c those that you never want to read at 8, those that offend your
+@c human rights at 9...
+
+
+The @dfn{group buffer} lists all (or parts) of the available groups. It
+is the first buffer shown when Gnus starts, and will never be killed as
+long as Gnus is active.
+
+@iftex
+@iflatex
+\gnusfigure{The Group Buffer}{320}{
+\put(75,50){\epsfig{figure=ps/group,height=9cm}}
+\put(120,37){\makebox(0,0)[t]{Buffer name}}
+\put(120,38){\vector(1,2){10}}
+\put(40,60){\makebox(0,0)[r]{Mode line}}
+\put(40,58){\vector(1,0){30}}
+\put(200,28){\makebox(0,0)[t]{Native select method}}
+\put(200,26){\vector(-1,2){15}}
+}
+@end iflatex
+@end iftex
+
+@menu
+* Group Buffer Format:: Information listed and how you can change it.
+* Group Maneuvering:: Commands for moving in the group buffer.
+* Selecting a Group:: Actually reading news.
+* Subscription Commands:: Unsubscribing, killing, subscribing.
+* Group Data:: Changing the info for a group.
+* Group Levels:: Levels? What are those, then?
+* Group Score:: A mechanism for finding out what groups you like.
+* Marking Groups:: You can mark groups for later processing.
+* Foreign Groups:: Creating and editing groups.
+* Group Parameters:: Each group may have different parameters set.
+* Listing Groups:: Gnus can list various subsets of the groups.
+* Sorting Groups:: Re-arrange the group order.
+* Group Maintenance:: Maintaining a tidy @file{.newsrc} file.
+* Browse Foreign Server:: You can browse a server. See what it has to offer.
+* Exiting Gnus:: Stop reading news and get some work done.
+* Group Topics:: A folding group mode divided into topics.
+* Non-ASCII Group Names:: Accessing groups of non-English names.
+* Misc Group Stuff:: Other stuff that you can to do.
+@end menu
+
+
+@node Group Buffer Format
+@section Group Buffer Format
+
+@menu
+* Group Line Specification:: Deciding how the group buffer is to look.
+* Group Mode Line Specification:: The group buffer mode line.
+* Group Highlighting:: Having nice colors in the group buffer.
+@end menu
+
+You can customize the Group Mode tool bar, see @kbd{M-x
+customize-apropos RET gnus-group-tool-bar}. This feature is only
+available in Emacs.
+
+The tool bar icons are now (de)activated correctly depending on the
+cursor position. Therefore, moving around in the Group Buffer is
+slower. You can disable this via the variable
+@code{gnus-group-update-tool-bar}. Its default value depends on your
+Emacs version.
+
+@node Group Line Specification
+@subsection Group Line Specification
+@cindex group buffer format
+
+The default format of the group buffer is nice and dull, but you can
+make it as exciting and ugly as you feel like.
+
+Here's a couple of example group lines:
+
+@example
+ 25: news.announce.newusers
+ * 0: alt.fan.andrea-dworkin
+@end example
+
+Quite simple, huh?
+
+You can see that there are 25 unread articles in
+@samp{news.announce.newusers}. There are no unread articles, but some
+ticked articles, in @samp{alt.fan.andrea-dworkin} (see that little
+asterisk at the beginning of the line?).
+
+@vindex gnus-group-line-format
+You can change that format to whatever you want by fiddling with the
+@code{gnus-group-line-format} variable. This variable works along the
+lines of a @code{format} specification, which is pretty much the same as
+a @code{printf} specifications, for those of you who use (feh!) C@.
+@xref{Formatting Variables}.
+
+@samp{%M%S%5y:%B%(%g%)\n} is the value that produced those lines above.
+
+There should always be a colon on the line; the cursor always moves to
+the colon after performing an operation. @xref{Positioning
+Point}. Nothing else is required---not even the group name. All
+displayed text is just window dressing, and is never examined by Gnus.
+Gnus stores all real information it needs using text properties.
+
+(Note that if you make a really strange, wonderful, spreadsheet-like
+layout, everybody will believe you are hard at work with the accounting
+instead of wasting time reading news.)
+
+Here's a list of all available format characters:
+
+@table @samp
+
+@item M
+An asterisk if the group only has marked articles.
+
+@item S
+Whether the group is subscribed.
+
+@item L
+Level of subscribedness.
+
+@item N
+Number of unread articles.
+
+@item I
+Number of dormant articles.
+
+@item T
+Number of ticked articles.
+
+@item R
+Number of read articles.
+
+@item U
+Number of unseen articles.
+
+@item t
+Estimated total number of articles. (This is really @var{max-number}
+minus @var{min-number} plus 1.)
+
+Gnus uses this estimation because the @acronym{NNTP} protocol provides
+efficient access to @var{max-number} and @var{min-number} but getting
+the true unread message count is not possible efficiently. For
+hysterical raisins, even the mail back ends, where the true number of
+unread messages might be available efficiently, use the same limited
+interface. To remove this restriction from Gnus means that the back
+end interface has to be changed, which is not an easy job.
+
+The nnml backend (@pxref{Mail Spool}) has a feature called ``group
+compaction'' which circumvents this deficiency: the idea is to
+renumber all articles from 1, removing all gaps between numbers, hence
+getting a correct total count. Other backends may support this in the
+future. In order to keep your total article count relatively up to
+date, you might want to compact your groups (or even directly your
+server) from time to time. @xref{Misc Group Stuff}, @xref{Server Commands}.
+
+@item y
+Number of unread, unticked, non-dormant articles.
+
+@item i
+Number of ticked and dormant articles.
+
+@item g
+Full group name.
+
+@item G
+Group name.
+
+@item C
+Group comment (@pxref{Group Parameters}) or group name if there is no
+comment element in the group parameters.
+
+@item D
+Newsgroup description. You need to read the group descriptions
+before these will appear, and to do that, you either have to set
+@code{gnus-read-active-file} or use the group buffer @kbd{M-d}
+command.
+
+@item o
+@samp{m} if moderated.
+
+@item O
+@samp{(m)} if moderated.
+
+@item s
+Select method.
+
+@item B
+If the summary buffer for the group is open or not.
+
+@item n
+Select from where.
+
+@item z
+A string that looks like @samp{<%s:%n>} if a foreign select method is
+used.
+
+@item P
+Indentation based on the level of the topic (@pxref{Group Topics}).
+
+@item c
+@vindex gnus-group-uncollapsed-levels
+Short (collapsed) group name. The @code{gnus-group-uncollapsed-levels}
+variable says how many levels to leave at the end of the group name.
+The default is 1---this will mean that group names like
+@samp{gnu.emacs.gnus} will be shortened to @samp{g.e.gnus}.
+
+@item m
+@vindex gnus-new-mail-mark
+@cindex %
+@samp{%} (@code{gnus-new-mail-mark}) if there has arrived new mail to
+the group lately.
+
+@item p
+@samp{#} (@code{gnus-process-mark}) if the group is process marked.
+
+@item d
+A string that says when you last read the group (@pxref{Group
+Timestamp}).
+
+@item F
+The disk space used by the articles fetched by both the cache and
+agent. The value is automatically scaled to bytes(B), kilobytes(K),
+megabytes(M), or gigabytes(G) to minimize the column width. A format
+of %7F is sufficient for a fixed-width column.
+
+@item u
+User defined specifier. The next character in the format string should
+be a letter. Gnus will call the function
+@code{gnus-user-format-function-}@samp{X}, where @samp{X} is the letter
+following @samp{%u}. The function will be passed a single dummy
+parameter as argument. The function should return a string, which will
+be inserted into the buffer just like information from any other
+specifier.
+@end table
+
+@cindex *
+All the ``number-of'' specs will be filled with an asterisk (@samp{*})
+if no info is available---for instance, if it is a non-activated foreign
+group, or a bogus native group.
+
+
+@node Group Mode Line Specification
+@subsection Group Mode Line Specification
+@cindex group mode line
+
+@vindex gnus-group-mode-line-format
+The mode line can be changed by setting
+@code{gnus-group-mode-line-format} (@pxref{Mode Line Formatting}). It
+doesn't understand that many format specifiers:
+
+@table @samp
+@item S
+The native news server.
+@item M
+The native select method.
+@end table
+
+
+@node Group Highlighting
+@subsection Group Highlighting
+@cindex highlighting
+@cindex group highlighting
+
+@vindex gnus-group-highlight
+Highlighting in the group buffer is controlled by the
+@code{gnus-group-highlight} variable. This is an alist with elements
+that look like @code{(@var{form} . @var{face})}. If @var{form} evaluates to
+something non-@code{nil}, the @var{face} will be used on the line.
+
+Here's an example value for this variable that might look nice if the
+background is dark:
+
+@lisp
+(cond (window-system
+ (setq custom-background-mode 'light)
+ (defface my-group-face-1
+ '((t (:foreground "Red" :bold t))) "First group face")
+ (defface my-group-face-2
+ '((t (:foreground "DarkSeaGreen4" :bold t)))
+ "Second group face")
+ (defface my-group-face-3
+ '((t (:foreground "Green4" :bold t))) "Third group face")
+ (defface my-group-face-4
+ '((t (:foreground "SteelBlue" :bold t))) "Fourth group face")
+ (defface my-group-face-5
+ '((t (:foreground "Blue" :bold t))) "Fifth group face")))
+
+(setq gnus-group-highlight
+ '(((> unread 200) . my-group-face-1)
+ ((and (< level 3) (zerop unread)) . my-group-face-2)
+ ((< level 3) . my-group-face-3)
+ ((zerop unread) . my-group-face-4)
+ (t . my-group-face-5)))
+@end lisp
+
+Also @pxref{Faces and Fonts}.
+
+Variables that are dynamically bound when the forms are evaluated
+include:
+
+@table @code
+@item group
+The group name.
+@item unread
+The number of unread articles in the group.
+@item method
+The select method.
+@item mailp
+Whether the group is a mail group.
+@item level
+The level of the group.
+@item score
+The score of the group.
+@item ticked
+The number of ticked articles in the group.
+@item total
+The total number of articles in the group. Or rather,
+@var{max-number} minus @var{min-number} plus one.
+@item topic
+When using the topic minor mode, this variable is bound to the current
+topic being inserted.
+@end table
+
+When the forms are @code{eval}ed, point is at the beginning of the line
+of the group in question, so you can use many of the normal Gnus
+functions for snarfing info on the group.
+
+@vindex gnus-group-update-hook
+@findex gnus-group-highlight-line
+@code{gnus-group-update-hook} is called when a group line is changed.
+It will not be called when @code{gnus-visual} is @code{nil}.
+
+
+@node Group Maneuvering
+@section Group Maneuvering
+@cindex group movement
+
+All movement commands understand the numeric prefix and will behave as
+expected, hopefully.
+
+@table @kbd
+
+@item n
+@kindex n (Group)
+@findex gnus-group-next-unread-group
+Go to the next group that has unread articles
+(@code{gnus-group-next-unread-group}).
+
+@item p
+@itemx DEL
+@kindex DEL (Group)
+@kindex p (Group)
+@findex gnus-group-prev-unread-group
+Go to the previous group that has unread articles
+(@code{gnus-group-prev-unread-group}).
+
+@item N
+@kindex N (Group)
+@findex gnus-group-next-group
+Go to the next group (@code{gnus-group-next-group}).
+
+@item P
+@kindex P (Group)
+@findex gnus-group-prev-group
+Go to the previous group (@code{gnus-group-prev-group}).
+
+@item M-n
+@kindex M-n (Group)
+@findex gnus-group-next-unread-group-same-level
+Go to the next unread group on the same (or lower) level
+(@code{gnus-group-next-unread-group-same-level}).
+
+@item M-p
+@kindex M-p (Group)
+@findex gnus-group-prev-unread-group-same-level
+Go to the previous unread group on the same (or lower) level
+(@code{gnus-group-prev-unread-group-same-level}).
+@end table
+
+Three commands for jumping to groups:
+
+@table @kbd
+
+@item j
+@kindex j (Group)
+@findex gnus-group-jump-to-group
+Jump to a group (and make it visible if it isn't already)
+(@code{gnus-group-jump-to-group}). Killed groups can be jumped to, just
+like living groups.
+
+@item ,
+@kindex , (Group)
+@findex gnus-group-best-unread-group
+Jump to the unread group with the lowest level
+(@code{gnus-group-best-unread-group}).
+
+@item .
+@kindex . (Group)
+@findex gnus-group-first-unread-group
+Jump to the first group with unread articles
+(@code{gnus-group-first-unread-group}).
+@end table
+
+@vindex gnus-group-goto-unread
+If @code{gnus-group-goto-unread} is @code{nil}, all the movement
+commands will move to the next group, not the next unread group. Even
+the commands that say they move to the next unread group. The default
+is @code{t}.
+
+@vindex gnus-summary-next-group-on-exit
+If @code{gnus-summary-next-group-on-exit} is @code{t}, when a summary is
+exited, the point in the group buffer is moved to the next unread group.
+Otherwise, the point is set to the group just exited. The default is
+@code{t}.
+
+@node Selecting a Group
+@section Selecting a Group
+@cindex group selection
+
+@table @kbd
+
+@item SPACE
+@kindex SPACE (Group)
+@findex gnus-group-read-group
+Select the current group, switch to the summary buffer and display the
+first unread article (@code{gnus-group-read-group}). If there are no
+unread articles in the group, or if you give a non-numerical prefix to
+this command, Gnus will offer to fetch all the old articles in this
+group from the server. If you give a numerical prefix @var{n}, @var{n}
+determines the number of articles Gnus will fetch. If @var{n} is
+positive, Gnus fetches the @var{n} newest articles, if @var{n} is
+negative, Gnus fetches the @code{abs(@var{n})} oldest articles.
+
+Thus, @kbd{SPC} enters the group normally, @kbd{C-u SPC} offers old
+articles, @kbd{C-u 4 2 SPC} fetches the 42 newest articles, and @kbd{C-u
+- 4 2 SPC} fetches the 42 oldest ones.
+
+When you are in the group (in the Summary buffer), you can type
+@kbd{M-g} to fetch new articles, or @kbd{C-u M-g} to also show the old
+ones.
+
+@item RET
+@kindex RET (Group)
+@findex gnus-group-select-group
+Select the current group and switch to the summary buffer
+(@code{gnus-group-select-group}). Takes the same arguments as
+@code{gnus-group-read-group}---the only difference is that this command
+does not display the first unread article automatically upon group
+entry.
+
+@item M-RET
+@kindex M-RET (Group)
+@findex gnus-group-quick-select-group
+This does the same as the command above, but tries to do it with the
+minimum amount of fuzz (@code{gnus-group-quick-select-group}). No
+scoring/killing will be performed, there will be no highlights and no
+expunging. This might be useful if you're in a real hurry and have to
+enter some humongous group. If you give a 0 prefix to this command
+(i.e., @kbd{0 M-RET}), Gnus won't even generate the summary buffer,
+which is useful if you want to toggle threading before generating the
+summary buffer (@pxref{Summary Generation Commands}).
+
+@item M-SPACE
+@kindex M-SPACE (Group)
+@findex gnus-group-visible-select-group
+This is yet one more command that does the same as the @kbd{RET}
+command, but this one does it without expunging and hiding dormants
+(@code{gnus-group-visible-select-group}).
+
+@item C-M-RET
+@kindex C-M-RET (Group)
+@findex gnus-group-select-group-ephemerally
+Finally, this command selects the current group ephemerally without
+doing any processing of its contents
+(@code{gnus-group-select-group-ephemerally}). Even threading has been
+turned off. Everything you do in the group after selecting it in this
+manner will have no permanent effects.
+
+@end table
+
+@vindex gnus-large-newsgroup
+The @code{gnus-large-newsgroup} variable says what Gnus should
+consider to be a big group. If it is @code{nil}, no groups are
+considered big. The default value is 200. If the group has more
+(unread and/or ticked) articles than this, Gnus will query the user
+before entering the group. The user can then specify how many
+articles should be fetched from the server. If the user specifies a
+negative number (@var{-n}), the @var{n} oldest articles will be
+fetched. If it is positive, the @var{n} articles that have arrived
+most recently will be fetched.
+
+@vindex gnus-large-ephemeral-newsgroup
+@code{gnus-large-ephemeral-newsgroup} is the same as
+@code{gnus-large-newsgroup}, but is only used for ephemeral
+newsgroups.
+
+@vindex gnus-newsgroup-maximum-articles
+In groups in some news servers, there might be a big gap between a few
+very old articles that will never be expired and the recent ones. In
+such a case, the server will return the data like @code{(1 . 30000000)}
+for the @code{LIST ACTIVE group} command, for example. Even if there
+are actually only the articles 1--10 and 29999900--30000000, Gnus doesn't
+know it at first and prepares for getting 30000000 articles. However,
+it will consume hundreds megabytes of memories and might make Emacs get
+stuck as the case may be. If you use such news servers, set the
+variable @code{gnus-newsgroup-maximum-articles} to a positive number.
+The value means that Gnus ignores articles other than this number of the
+latest ones in every group. For instance, the value 10000 makes Gnus
+get only the articles 29990001--30000000 (if the latest article number is
+30000000 in a group). Note that setting this variable to a number might
+prevent you from reading very old articles. The default value of the
+variable @code{gnus-newsgroup-maximum-articles} is @code{nil}, which
+means Gnus never ignores old articles.
+
+@vindex gnus-select-group-hook
+@vindex gnus-auto-select-first
+@vindex gnus-auto-select-subject
+If @code{gnus-auto-select-first} is non-@code{nil}, select an article
+automatically when entering a group with the @kbd{SPACE} command.
+Which article this is controlled by the
+@code{gnus-auto-select-subject} variable. Valid values for this
+variable are:
+
+@table @code
+
+@item unread
+Place point on the subject line of the first unread article.
+
+@item first
+Place point on the subject line of the first article.
+
+@item unseen
+Place point on the subject line of the first unseen article.
+
+@item unseen-or-unread
+Place point on the subject line of the first unseen article, and if
+there is no such article, place point on the subject line of the first
+unread article.
+
+@item best
+Place point on the subject line of the highest-scored unread article.
+
+@end table
+
+This variable can also be a function. In that case, that function
+will be called to place point on a subject line.
+
+If you want to prevent automatic selection in some group (say, in a
+binary group with Huge articles) you can set the
+@code{gnus-auto-select-first} variable to @code{nil} in
+@code{gnus-select-group-hook}, which is called when a group is
+selected.
+
+
+@node Subscription Commands
+@section Subscription Commands
+@cindex subscription
+
+The following commands allow for managing your subscriptions in the
+Group buffer. If you want to subscribe to many groups, it's probably
+more convenient to go to the @ref{Server Buffer}, and choose the
+server there using @kbd{RET} or @kbd{SPC}. Then you'll have the
+commands listed in @ref{Browse Foreign Server} at hand.
+
+@table @kbd
+
+@item S t
+@itemx u
+@kindex S t (Group)
+@kindex u (Group)
+@findex gnus-group-unsubscribe-current-group
+@c @icon{gnus-group-unsubscribe}
+Toggle subscription to the current group
+(@code{gnus-group-unsubscribe-current-group}).
+
+@item S s
+@itemx U
+@kindex S s (Group)
+@kindex U (Group)
+@findex gnus-group-unsubscribe-group
+Prompt for a group to subscribe, and then subscribe it. If it was
+subscribed already, unsubscribe it instead
+(@code{gnus-group-unsubscribe-group}).
+
+@item S k
+@itemx C-k
+@kindex S k (Group)
+@kindex C-k (Group)
+@findex gnus-group-kill-group
+@c @icon{gnus-group-kill-group}
+Kill the current group (@code{gnus-group-kill-group}).
+
+@item S y
+@itemx C-y
+@kindex S y (Group)
+@kindex C-y (Group)
+@findex gnus-group-yank-group
+Yank the last killed group (@code{gnus-group-yank-group}).
+
+@item C-x C-t
+@kindex C-x C-t (Group)
+@findex gnus-group-transpose-groups
+Transpose two groups (@code{gnus-group-transpose-groups}). This isn't
+really a subscription command, but you can use it instead of a
+kill-and-yank sequence sometimes.
+
+@item S w
+@itemx C-w
+@kindex S w (Group)
+@kindex C-w (Group)
+@findex gnus-group-kill-region
+Kill all groups in the region (@code{gnus-group-kill-region}).
+
+@item S z
+@kindex S z (Group)
+@findex gnus-group-kill-all-zombies
+Kill all zombie groups (@code{gnus-group-kill-all-zombies}).
+
+@item S C-k
+@kindex S C-k (Group)
+@findex gnus-group-kill-level
+Kill all groups on a certain level (@code{gnus-group-kill-level}).
+These groups can't be yanked back after killing, so this command should
+be used with some caution. The only time where this command comes in
+really handy is when you have a @file{.newsrc} with lots of unsubscribed
+groups that you want to get rid off. @kbd{S C-k} on level 7 will
+kill off all unsubscribed groups that do not have message numbers in the
+@file{.newsrc} file.
+
+@end table
+
+Also @pxref{Group Levels}.
+
+
+@node Group Data
+@section Group Data
+
+@table @kbd
+
+@item c
+@kindex c (Group)
+@findex gnus-group-catchup-current
+@vindex gnus-group-catchup-group-hook
+@c @icon{gnus-group-catchup-current}
+Mark all unticked articles in this group as read
+(@code{gnus-group-catchup-current}).
+@code{gnus-group-catchup-group-hook} is called when catching up a group from
+the group buffer.
+
+@item C
+@kindex C (Group)
+@findex gnus-group-catchup-current-all
+Mark all articles in this group, even the ticked ones, as read
+(@code{gnus-group-catchup-current-all}).
+
+@item M-c
+@kindex M-c (Group)
+@findex gnus-group-clear-data
+Clear the data from the current group---nix out marks and the list of
+read articles (@code{gnus-group-clear-data}).
+
+@item M-x gnus-group-clear-data-on-native-groups
+@kindex M-x gnus-group-clear-data-on-native-groups
+@findex gnus-group-clear-data-on-native-groups
+If you have switched from one @acronym{NNTP} server to another, all your marks
+and read ranges have become worthless. You can use this command to
+clear out all data that you have on your native groups. Use with
+caution.
+
+@end table
+
+
+@node Group Levels
+@section Group Levels
+@cindex group level
+@cindex level
+
+All groups have a level of @dfn{subscribedness}. For instance, if a
+group is on level 2, it is more subscribed than a group on level 5. You
+can ask Gnus to just list groups on a given level or lower
+(@pxref{Listing Groups}), or to just check for new articles in groups on
+a given level or lower (@pxref{Scanning New Messages}).
+
+Remember: The higher the level of the group, the less important it is.
+
+@table @kbd
+
+@item S l
+@kindex S l (Group)
+@findex gnus-group-set-current-level
+Set the level of the current group. If a numeric prefix is given, the
+next @var{n} groups will have their levels set. The user will be
+prompted for a level.
+@end table
+
+@vindex gnus-level-killed
+@vindex gnus-level-zombie
+@vindex gnus-level-unsubscribed
+@vindex gnus-level-subscribed
+Gnus considers groups from levels 1 to
+@code{gnus-level-subscribed} (inclusive) (default 5) to be subscribed,
+@code{gnus-level-subscribed} (exclusive) and
+@code{gnus-level-unsubscribed} (inclusive) (default 7) to be
+unsubscribed, @code{gnus-level-zombie} to be zombies (walking dead)
+(default 8) and @code{gnus-level-killed} to be killed (completely dead)
+(default 9). Gnus treats subscribed and unsubscribed groups exactly the
+same, but zombie and killed groups store no information on what articles
+you have read, etc. This distinction between dead and living
+groups isn't done because it is nice or clever, it is done purely for
+reasons of efficiency.
+
+It is recommended that you keep all your mail groups (if any) on quite
+low levels (e.g., 1 or 2).
+
+Maybe the following description of the default behavior of Gnus helps to
+understand what these levels are all about. By default, Gnus shows you
+subscribed nonempty groups, but by hitting @kbd{L} you can have it show
+empty subscribed groups and unsubscribed groups, too. Type @kbd{l} to
+go back to showing nonempty subscribed groups again. Thus, unsubscribed
+groups are hidden, in a way.
+
+@cindex zombie groups
+Zombie and killed groups are similar to unsubscribed groups in that they
+are hidden by default. But they are different from subscribed and
+unsubscribed groups in that Gnus doesn't ask the news server for
+information (number of messages, number of unread messages) on zombie
+and killed groups. Normally, you use @kbd{C-k} to kill the groups you
+aren't interested in. If most groups are killed, Gnus is faster.
+
+Why does Gnus distinguish between zombie and killed groups? Well, when
+a new group arrives on the server, Gnus by default makes it a zombie
+group. This means that you are normally not bothered with new groups,
+but you can type @kbd{A z} to get a list of all new groups. Subscribe
+the ones you like and kill the ones you don't want. (@kbd{A k} shows a
+list of killed groups.)
+
+If you want to play with the level variables, you should show some care.
+Set them once, and don't touch them ever again. Better yet, don't touch
+them at all unless you know exactly what you're doing.
+
+@vindex gnus-level-default-unsubscribed
+@vindex gnus-level-default-subscribed
+Two closely related variables are @code{gnus-level-default-subscribed}
+(default 3) and @code{gnus-level-default-unsubscribed} (default 6),
+which are the levels that new groups will be put on if they are
+(un)subscribed. These two variables should, of course, be inside the
+relevant valid ranges.
+
+@vindex gnus-keep-same-level
+If @code{gnus-keep-same-level} is non-@code{nil}, some movement commands
+will only move to groups of the same level (or lower). In
+particular, going from the last article in one group to the next group
+will go to the next group of the same level (or lower). This might be
+handy if you want to read the most important groups before you read the
+rest.
+
+If this variable is @code{best}, Gnus will make the next newsgroup the
+one with the best level.
+
+@vindex gnus-group-default-list-level
+All groups with a level less than or equal to
+@code{gnus-group-default-list-level} will be listed in the group buffer
+by default.
+This variable can also be a function. In that case, that function will
+be called and the result will be used as value.
+
+
+@vindex gnus-group-list-inactive-groups
+If @code{gnus-group-list-inactive-groups} is non-@code{nil}, non-active
+groups will be listed along with the unread groups. This variable is
+@code{t} by default. If it is @code{nil}, inactive groups won't be
+listed.
+
+@vindex gnus-group-use-permanent-levels
+If @code{gnus-group-use-permanent-levels} is non-@code{nil}, once you
+give a level prefix to @kbd{g} or @kbd{l}, all subsequent commands will
+use this level as the ``work'' level.
+
+@vindex gnus-activate-level
+Gnus will normally just activate (i.e., query the server about) groups
+on level @code{gnus-activate-level} or less. If you don't want to
+activate unsubscribed groups, for instance, you might set this variable
+to 5. The default is 6.
+
+
+@node Group Score
+@section Group Score
+@cindex group score
+@cindex group rank
+@cindex rank
+
+You would normally keep important groups on high levels, but that scheme
+is somewhat restrictive. Don't you wish you could have Gnus sort the
+group buffer according to how often you read groups, perhaps? Within
+reason?
+
+This is what @dfn{group score} is for. You can have Gnus assign a score
+to each group through the mechanism described below. You can then sort
+the group buffer based on this score. Alternatively, you can sort on
+score and then level. (Taken together, the level and the score is
+called the @dfn{rank} of the group. A group that is on level 4 and has
+a score of 1 has a higher rank than a group on level 5 that has a score
+of 300. (The level is the most significant part and the score is the
+least significant part.))
+
+@findex gnus-summary-bubble-group
+If you want groups you read often to get higher scores than groups you
+read seldom you can add the @code{gnus-summary-bubble-group} function to
+the @code{gnus-summary-exit-hook} hook. This will result (after
+sorting) in a bubbling sort of action. If you want to see that in
+action after each summary exit, you can add
+@code{gnus-group-sort-groups-by-rank} or
+@code{gnus-group-sort-groups-by-score} to the same hook, but that will
+slow things down somewhat.
+
+
+@node Marking Groups
+@section Marking Groups
+@cindex marking groups
+
+If you want to perform some command on several groups, and they appear
+subsequently in the group buffer, you would normally just give a
+numerical prefix to the command. Most group commands will then do your
+bidding on those groups.
+
+However, if the groups are not in sequential order, you can still
+perform a command on several groups. You simply mark the groups first
+with the process mark and then execute the command.
+
+@table @kbd
+
+@item #
+@kindex # (Group)
+@itemx M m
+@kindex M m (Group)
+@findex gnus-group-mark-group
+Set the mark on the current group (@code{gnus-group-mark-group}).
+
+@item M-#
+@kindex M-# (Group)
+@itemx M u
+@kindex M u (Group)
+@findex gnus-group-unmark-group
+Remove the mark from the current group
+(@code{gnus-group-unmark-group}).
+
+@item M U
+@kindex M U (Group)
+@findex gnus-group-unmark-all-groups
+Remove the mark from all groups (@code{gnus-group-unmark-all-groups}).
+
+@item M w
+@kindex M w (Group)
+@findex gnus-group-mark-region
+Mark all groups between point and mark (@code{gnus-group-mark-region}).
+
+@item M b
+@kindex M b (Group)
+@findex gnus-group-mark-buffer
+Mark all groups in the buffer (@code{gnus-group-mark-buffer}).
+
+@item M r
+@kindex M r (Group)
+@findex gnus-group-mark-regexp
+Mark all groups that match some regular expression
+(@code{gnus-group-mark-regexp}).
+@end table
+
+Also @pxref{Process/Prefix}.
+
+@findex gnus-group-universal-argument
+If you want to execute some command on all groups that have been marked
+with the process mark, you can use the @kbd{M-&}
+(@code{gnus-group-universal-argument}) command. It will prompt you for
+the command to be executed.
+
+
+@node Foreign Groups
+@section Foreign Groups
+@cindex foreign groups
+
+If you recall how to subscribe to servers (@pxref{Finding the News})
+you will remember that @code{gnus-secondary-select-methods} and
+@code{gnus-select-method} let you write a definition in Emacs Lisp of
+what servers you want to see when you start up. The alternate
+approach is to use foreign servers and groups. ``Foreign'' here means
+they are not coming from the select methods. All foreign server
+configuration and subscriptions are stored only in the
+@file{~/.newsrc.eld} file.
+
+Below are some group mode commands for making and editing general foreign
+groups, as well as commands to ease the creation of a few
+special-purpose groups. All these commands insert the newly created
+groups under point---@code{gnus-subscribe-newsgroup-method} is not
+consulted.
+
+Changes from the group editing commands are stored in
+@file{~/.newsrc.eld} (@code{gnus-startup-file}). An alternative is the
+variable @code{gnus-parameters}, @xref{Group Parameters}.
+
+@table @kbd
+
+@item G m
+@kindex G m (Group)
+@findex gnus-group-make-group
+@cindex making groups
+Make a new group (@code{gnus-group-make-group}). Gnus will prompt you
+for a name, a method and possibly an @dfn{address}. For an easier way
+to subscribe to @acronym{NNTP} groups (@pxref{Browse Foreign Server}).
+
+@item G M
+@kindex G M (Group)
+@findex gnus-group-read-ephemeral-group
+Make an ephemeral group (@code{gnus-group-read-ephemeral-group}). Gnus
+will prompt you for a name, a method and an @dfn{address}.
+
+@item G r
+@kindex G r (Group)
+@findex gnus-group-rename-group
+@cindex renaming groups
+Rename the current group to something else
+(@code{gnus-group-rename-group}). This is valid only on some
+groups---mail groups mostly. This command might very well be quite slow
+on some back ends.
+
+@item G c
+@kindex G c (Group)
+@cindex customizing
+@findex gnus-group-customize
+Customize the group parameters (@code{gnus-group-customize}).
+
+@item G e
+@kindex G e (Group)
+@findex gnus-group-edit-group-method
+@cindex renaming groups
+Enter a buffer where you can edit the select method of the current
+group (@code{gnus-group-edit-group-method}).
+
+@item G p
+@kindex G p (Group)
+@findex gnus-group-edit-group-parameters
+Enter a buffer where you can edit the group parameters
+(@code{gnus-group-edit-group-parameters}).
+
+@item G E
+@kindex G E (Group)
+@findex gnus-group-edit-group
+Enter a buffer where you can edit the group info
+(@code{gnus-group-edit-group}).
+
+@item G d
+@kindex G d (Group)
+@findex gnus-group-make-directory-group
+@cindex nndir
+Make a directory group (@pxref{Directory Groups}). You will be prompted
+for a directory name (@code{gnus-group-make-directory-group}).
+
+@item G h
+@kindex G h (Group)
+@cindex help group
+@findex gnus-group-make-help-group
+Make the Gnus help group (@code{gnus-group-make-help-group}).
+
+@item G D
+@kindex G D (Group)
+@findex gnus-group-enter-directory
+@cindex nneething
+Read an arbitrary directory as if it were a newsgroup with the
+@code{nneething} back end (@code{gnus-group-enter-directory}).
+@xref{Anything Groups}.
+
+@item G f
+@kindex G f (Group)
+@findex gnus-group-make-doc-group
+@cindex ClariNet Briefs
+@cindex nndoc
+Make a group based on some file or other
+(@code{gnus-group-make-doc-group}). If you give a prefix to this
+command, you will be prompted for a file name and a file type.
+Currently supported types are @code{mbox}, @code{babyl},
+@code{digest}, @code{news}, @code{rnews}, @code{mmdf}, @code{forward},
+@code{rfc934}, @code{rfc822-forward}, @code{mime-parts},
+@code{standard-digest}, @code{slack-digest}, @code{clari-briefs},
+@code{nsmail}, @code{outlook}, @code{oe-dbx}, and @code{mailman}. If
+you run this command without a prefix, Gnus will guess at the file
+type. @xref{Document Groups}.
+
+@item G u
+@kindex G u (Group)
+@vindex gnus-useful-groups
+@findex gnus-group-make-useful-group
+Create one of the groups mentioned in @code{gnus-useful-groups}
+(@code{gnus-group-make-useful-group}).
+
+@item G w
+@kindex G w (Group)
+@findex gnus-group-make-web-group
+@cindex Google
+@cindex nnweb
+@cindex gmane
+Make an ephemeral group based on a web search
+(@code{gnus-group-make-web-group}). If you give a prefix to this
+command, make a solid group instead. You will be prompted for the
+search engine type and the search string. Valid search engine types
+include @code{google}, @code{dejanews}, and @code{gmane}.
+@xref{Web Searches}.
+
+If you use the @code{google} search engine, you can limit the search
+to a particular group by using a match string like
+@samp{shaving group:alt.sysadmin.recovery}.
+
+@item G R
+@kindex G R (Group)
+@findex gnus-group-make-rss-group
+Make a group based on an @acronym{RSS} feed
+(@code{gnus-group-make-rss-group}). You will be prompted for an URL@.
+@xref{RSS}.
+
+@item G DEL
+@kindex G DEL (Group)
+@findex gnus-group-delete-group
+This function will delete the current group
+(@code{gnus-group-delete-group}). If given a prefix, this function will
+actually delete all the articles in the group, and forcibly remove the
+group itself from the face of the Earth. Use a prefix only if you are
+absolutely sure of what you are doing. This command can't be used on
+read-only groups (like @code{nntp} groups), though.
+
+@item G V
+@kindex G V (Group)
+@findex gnus-group-make-empty-virtual
+Make a new, fresh, empty @code{nnvirtual} group
+(@code{gnus-group-make-empty-virtual}). @xref{Virtual Groups}.
+
+@item G v
+@kindex G v (Group)
+@findex gnus-group-add-to-virtual
+Add the current group to an @code{nnvirtual} group
+(@code{gnus-group-add-to-virtual}). Uses the process/prefix convention.
+@end table
+
+@xref{Select Methods}, for more information on the various select
+methods.
+
+@vindex gnus-activate-foreign-newsgroups
+If @code{gnus-activate-foreign-newsgroups} is a positive number,
+Gnus will check all foreign groups with this level or lower at startup.
+This might take quite a while, especially if you subscribe to lots of
+groups from different @acronym{NNTP} servers. Also @pxref{Group Levels};
+@code{gnus-activate-level} also affects activation of foreign
+newsgroups.
+
+
+The following commands create ephemeral groups. They can be called not
+only from the Group buffer, but in any Gnus buffer.
+
+@table @code
+@item gnus-read-ephemeral-gmane-group
+@findex gnus-read-ephemeral-gmane-group
+@vindex gnus-gmane-group-download-format
+Read an ephemeral group on Gmane.org. The articles are downloaded via
+HTTP using the URL specified by @code{gnus-gmane-group-download-format}.
+Gnus will prompt you for a group name, the start article number and an
+the article range.
+
+@item gnus-read-ephemeral-gmane-group-url
+@findex gnus-read-ephemeral-gmane-group-url
+This command is similar to @code{gnus-read-ephemeral-gmane-group}, but
+the group name and the article number and range are constructed from a
+given @acronym{URL}. Supported @acronym{URL} formats include:
+@indicateurl{http://thread.gmane.org/gmane.foo.bar/12300/focus=12399},
+@indicateurl{http://thread.gmane.org/gmane.foo.bar/12345/},
+@indicateurl{http://article.gmane.org/gmane.foo.bar/12345/},
+@indicateurl{http://permalink.gmane.org/gmane.foo.bar/12345/}, and
+@indicateurl{http://news.gmane.org/group/gmane.foo.bar/thread=12345}.
+
+@item gnus-read-ephemeral-emacs-bug-group
+@findex gnus-read-ephemeral-emacs-bug-group
+Read an Emacs bug report in an ephemeral group. Gnus will prompt for a
+bug number. The default is the number at point. The @acronym{URL} is
+specified in @code{gnus-bug-group-download-format-alist}.
+
+@item gnus-read-ephemeral-debian-bug-group
+@findex gnus-read-ephemeral-debian-bug-group
+Read a Debian bug report in an ephemeral group. Analog to
+@code{gnus-read-ephemeral-emacs-bug-group}.
+@end table
+
+Some of these command are also useful for article buttons, @xref{Article
+Buttons}.
+
+Here is an example:
+@lisp
+(require 'gnus-art)
+(add-to-list
+ 'gnus-button-alist
+ '("#\\([0-9]+\\)\\>" 1
+ (string-match "\\<emacs\\>" (or gnus-newsgroup-name ""))
+ gnus-read-ephemeral-emacs-bug-group 1))
+@end lisp
+
+
+@node Group Parameters
+@section Group Parameters
+@cindex group parameters
+
+The group parameters store information local to a particular group.
+
+Use the @kbd{G p} or the @kbd{G c} command to edit group parameters of a
+group. (@kbd{G p} presents you with a Lisp-based interface, @kbd{G c}
+presents you with a Customize-like interface. The latter helps avoid
+silly Lisp errors.) You might also be interested in reading about topic
+parameters (@pxref{Topic Parameters}).
+Additionally, you can set group parameters via the
+@code{gnus-parameters} variable, see below.
+
+Here's an example group parameter list:
+
+@example
+((to-address . "ding@@gnus.org")
+ (auto-expire . t))
+@end example
+
+We see that each element consists of a ``dotted pair''---the thing before
+the dot is the key, while the thing after the dot is the value. All the
+parameters have this form @emph{except} local variable specs, which are
+not dotted pairs, but proper lists.
+
+Some parameters have correspondent customizable variables, each of which
+is an alist of regexps and values.
+
+The following group parameters can be used:
+
+@table @code
+@item to-address
+@cindex to-address
+Address used by when doing followups and new posts.
+
+@example
+(to-address . "some@@where.com")
+@end example
+
+This is primarily useful in mail groups that represent closed mailing
+lists---mailing lists where it's expected that everybody that writes to
+the mailing list is subscribed to it. Since using this parameter
+ensures that the mail only goes to the mailing list itself, it means
+that members won't receive two copies of your followups.
+
+Using @code{to-address} will actually work whether the group is foreign
+or not. Let's say there's a group on the server that is called
+@samp{fa.4ad-l}. This is a real newsgroup, but the server has gotten
+the articles from a mail-to-news gateway. Posting directly to this
+group is therefore impossible---you have to send mail to the mailing
+list address instead.
+
+See also @code{gnus-parameter-to-address-alist}.
+
+@item to-list
+@cindex to-list
+Address used when doing @kbd{a} in that group.
+
+@example
+(to-list . "some@@where.com")
+@end example
+
+It is totally ignored
+when doing a followup---except that if it is present in a news group,
+you'll get mail group semantics when doing @kbd{f}.
+
+If you do an @kbd{a} command in a mail group and you have neither a
+@code{to-list} group parameter nor a @code{to-address} group parameter,
+then a @code{to-list} group parameter will be added automatically upon
+sending the message if @code{gnus-add-to-list} is set to @code{t}.
+@vindex gnus-add-to-list
+
+@findex gnus-mailing-list-mode
+@cindex mail list groups
+If this variable is set, @code{gnus-mailing-list-mode} is turned on when
+entering summary buffer.
+
+See also @code{gnus-parameter-to-list-alist}.
+
+@anchor{subscribed}
+@item subscribed
+@cindex subscribed
+@cindex Mail-Followup-To
+@findex gnus-find-subscribed-addresses
+If this parameter is set to @code{t}, Gnus will consider the
+to-address and to-list parameters for this group as addresses of
+mailing lists you are subscribed to. Giving Gnus this information is
+(only) a first step in getting it to generate correct Mail-Followup-To
+headers for your posts to these lists. The second step is to put the
+following in your @file{.gnus.el}
+
+@lisp
+(setq message-subscribed-address-functions
+ '(gnus-find-subscribed-addresses))
+@end lisp
+
+@xref{Mailing Lists, ,Mailing Lists, message, The Message Manual}, for
+a complete treatment of available MFT support.
+
+@item visible
+@cindex visible
+If the group parameter list has the element @code{(visible . t)},
+that group will always be visible in the Group buffer, regardless
+of whether it has any unread articles.
+
+This parameter cannot be set via @code{gnus-parameters}. See
+@code{gnus-permanently-visible-groups} as an alternative.
+
+@item broken-reply-to
+@cindex broken-reply-to
+Elements like @code{(broken-reply-to . t)} signals that @code{Reply-To}
+headers in this group are to be ignored, and for the header to be hidden
+if @code{reply-to} is part of @code{gnus-boring-article-headers}. This
+can be useful if you're reading a mailing list group where the listserv
+has inserted @code{Reply-To} headers that point back to the listserv
+itself. That is broken behavior. So there!
+
+@item to-group
+@cindex to-group
+Elements like @code{(to-group . "some.group.name")} means that all
+posts in that group will be sent to @code{some.group.name}.
+
+@item newsgroup
+@cindex newsgroup
+If you have @code{(newsgroup . t)} in the group parameter list, Gnus
+will treat all responses as if they were responses to news articles.
+This can be useful if you have a mail group that's really a mirror of a
+news group.
+
+@item gcc-self
+@cindex gcc-self
+If @code{(gcc-self . t)} is present in the group parameter list, newly
+composed messages will be @code{gcc}d to the current group. If
+@code{(gcc-self . none)} is present, no @code{Gcc:} header will be
+generated, if @code{(gcc-self . "group")} is present, this string will
+be inserted literally as a @code{Gcc:} header. It should be a group
+name. The @code{gcc-self} value may also be a list of strings and
+@code{t}, e.g., @code{(gcc-self "group1" "group2" t)} means to
+@code{gcc} the newly composed message into the groups @code{"group1"}
+and @code{"group2"}, and into the current group. The @code{gcc-self}
+parameter takes precedence over any default @code{Gcc} rules as
+described later (@pxref{Archived Messages}), with the exception for
+messages to resend.
+
+@strong{Caveat}: Adding @code{(gcc-self . t)} to the parameter list of
+@code{nntp} groups (or the like) isn't valid. An @code{nntp} server
+doesn't accept articles.
+
+@item auto-expire
+@cindex auto-expire
+@cindex expiring mail
+If the group parameter has an element that looks like @code{(auto-expire
+. t)}, all articles read will be marked as expirable. For an
+alternative approach, @pxref{Expiring Mail}.
+
+See also @code{gnus-auto-expirable-newsgroups}.
+
+@item total-expire
+@cindex total-expire
+@cindex expiring mail
+If the group parameter has an element that looks like
+@code{(total-expire . t)}, all read articles will be put through the
+expiry process, even if they are not marked as expirable. Use with
+caution. Unread, ticked and dormant articles are not eligible for
+expiry.
+
+See also @code{gnus-total-expirable-newsgroups}.
+
+@item expiry-wait
+@cindex expiry-wait
+@vindex nnmail-expiry-wait-function
+If the group parameter has an element that looks like
+@code{(expiry-wait . 10)}, this value will override any
+@code{nnmail-expiry-wait} and @code{nnmail-expiry-wait-function}
+(@pxref{Expiring Mail}) when expiring expirable messages. The value
+can either be a number of days (not necessarily an integer) or the
+symbols @code{never} or @code{immediate}.
+
+@item expiry-target
+@cindex expiry-target
+Where expired messages end up. This parameter overrides
+@code{nnmail-expiry-target}.
+
+@item score-file
+@cindex score file group parameter
+Elements that look like @code{(score-file . "file")} will make
+@file{file} into the current score file for the group in question. All
+interactive score entries will be put into this file.
+
+@item adapt-file
+@cindex adapt file group parameter
+Elements that look like @code{(adapt-file . "file")} will make
+@file{file} into the current adaptive file for the group in question.
+All adaptive score entries will be put into this file.
+
+@item admin-address
+@cindex admin-address
+When unsubscribing from a mailing list you should never send the
+unsubscription notice to the mailing list itself. Instead, you'd send
+messages to the administrative address. This parameter allows you to
+put the admin address somewhere convenient.
+
+@item display
+@cindex display
+Elements that look like @code{(display . MODE)} say which articles to
+display on entering the group. Valid values are:
+
+@table @code
+@item all
+Display all articles, both read and unread.
+
+@item an integer
+Display the last @var{integer} articles in the group. This is the same as
+entering the group with @kbd{C-u @var{integer}}.
+
+@item default
+Display the default visible articles, which normally includes unread and
+ticked articles.
+
+@item an array
+Display articles that satisfy a predicate.
+
+Here are some examples:
+
+@table @code
+@item [unread]
+Display only unread articles.
+
+@item [not expire]
+Display everything except expirable articles.
+
+@item [and (not reply) (not expire)]
+Display everything except expirable and articles you've already
+responded to.
+@end table
+
+The available operators are @code{not}, @code{and} and @code{or}.
+Predicates include @code{tick}, @code{unsend}, @code{undownload},
+@code{unread}, @code{dormant}, @code{expire}, @code{reply},
+@code{killed}, @code{bookmark}, @code{score}, @code{save},
+@code{cache}, @code{forward}, and @code{unseen}.
+
+@end table
+
+The @code{display} parameter works by limiting the summary buffer to
+the subset specified. You can pop the limit by using the @kbd{/ w}
+command (@pxref{Limiting}).
+
+@item comment
+@cindex comment
+Elements that look like @code{(comment . "This is a comment")} are
+arbitrary comments on the group. You can display comments in the
+group line (@pxref{Group Line Specification}).
+
+@item charset
+@cindex charset
+Elements that look like @code{(charset . iso-8859-1)} will make
+@code{iso-8859-1} the default charset; that is, the charset that will be
+used for all articles that do not specify a charset.
+
+See also @code{gnus-group-charset-alist}.
+
+@item ignored-charsets
+@cindex ignored-charset
+Elements that look like @code{(ignored-charsets x-unknown iso-8859-1)}
+will make @code{iso-8859-1} and @code{x-unknown} ignored; that is, the
+default charset will be used for decoding articles.
+
+See also @code{gnus-group-ignored-charsets-alist}.
+
+@item posting-style
+@cindex posting-style
+You can store additional posting style information for this group
+here (@pxref{Posting Styles}). The format is that of an entry in the
+@code{gnus-posting-styles} alist, except that there's no regexp matching
+the group name (of course). Style elements in this group parameter will
+take precedence over the ones found in @code{gnus-posting-styles}.
+
+For instance, if you want a funky name and signature in this group only,
+instead of hacking @code{gnus-posting-styles}, you could put something
+like this in the group parameters:
+
+@example
+(posting-style
+ (name "Funky Name")
+ ("X-Message-SMTP-Method" "smtp smtp.example.org 587")
+ ("X-My-Header" "Funky Value")
+ (signature "Funky Signature"))
+@end example
+
+If you're using topics to organize your group buffer
+(@pxref{Group Topics}), note that posting styles can also be set in
+the topics parameters. Posting styles in topic parameters apply to all
+groups in this topic. More precisely, the posting-style settings for a
+group result from the hierarchical merging of all posting-style
+entries in the parameters of this group and all the topics it belongs
+to.
+
+
+@item post-method
+@cindex post-method
+If it is set, the value is used as the method for posting message
+instead of @code{gnus-post-method}.
+
+@item mail-source
+@cindex mail-source
+If it is set, and the setting of @code{mail-sources} includes a
+@code{group} mail source (@pxref{Mail Sources}), the value is a
+mail source for this group.
+
+@item banner
+@cindex banner
+An item like @code{(banner . @var{regexp})} causes any part of an article
+that matches the regular expression @var{regexp} to be stripped. Instead of
+@var{regexp}, you can also use the symbol @code{signature} which strips the
+last signature or any of the elements of the alist
+@code{gnus-article-banner-alist}.
+
+@item sieve
+@cindex sieve
+This parameter contains a Sieve test that should match incoming mail
+that should be placed in this group. From this group parameter, a
+Sieve @samp{IF} control structure is generated, having the test as the
+condition and @samp{fileinto "group.name";} as the body.
+
+For example, if the @samp{INBOX.list.sieve} group has the @code{(sieve
+address "sender" "sieve-admin@@extundo.com")} group parameter, when
+translating the group parameter into a Sieve script (@pxref{Sieve
+Commands}) the following Sieve code is generated:
+
+@example
+if address "sender" "sieve-admin@@extundo.com" @{
+ fileinto "INBOX.list.sieve";
+@}
+@end example
+
+To generate tests for multiple email-addresses use a group parameter
+like @code{(sieve address "sender" ("name@@one.org" else@@two.org"))}.
+When generating a sieve script (@pxref{Sieve Commands}) Sieve code
+like the following is generated:
+
+@example
+if address "sender" ["name@@one.org", "else@@two.org"] @{
+ fileinto "INBOX.list.sieve";
+@}
+@end example
+
+You can also use regexp expansions in the rules:
+
+@example
+(sieve header :regex "list-id" "<c++std-\\1.accu.org>")
+@end example
+
+See @pxref{Sieve Commands} for commands and variables that might be of
+interest in relation to the sieve parameter.
+
+The Sieve language is described in RFC 3028. @xref{Top, Emacs Sieve,
+Top, sieve, Emacs Sieve}.
+
+@item (agent parameters)
+If the agent has been enabled, you can set any of its parameters to
+control the behavior of the agent in individual groups. See Agent
+Parameters in @ref{Category Syntax}. Most users will choose to set
+agent parameters in either an agent category or group topic to
+minimize the configuration effort.
+
+@item (@var{variable} @var{form})
+You can use the group parameters to set variables local to the group you
+are entering. If you want to turn threading off in @samp{news.answers},
+you could put @code{(gnus-show-threads nil)} in the group parameters of
+that group. @code{gnus-show-threads} will be made into a local variable
+in the summary buffer you enter, and the form @code{nil} will be
+@code{eval}ed there.
+
+Note that this feature sets the variable locally to the summary buffer
+if and only if @var{variable} has been bound as a variable. Otherwise,
+only evaluating the form will take place. So, you may want to bind the
+variable in advance using @code{defvar} or other if the result of the
+form needs to be set to it.
+
+But some variables are evaluated in the article buffer, or in the
+message buffer (of a reply or followup or otherwise newly created
+message). As a workaround, it might help to add the variable in
+question to @code{gnus-newsgroup-variables}. @xref{Various Summary
+Stuff}. So if you want to set @code{message-from-style} via the group
+parameters, then you may need the following statement elsewhere in your
+@file{~/.gnus.el} file:
+
+@lisp
+(add-to-list 'gnus-newsgroup-variables 'message-from-style)
+@end lisp
+
+@vindex gnus-list-identifiers
+A use for this feature is to remove a mailing list identifier tag in
+the subject fields of articles. E.g., if the news group
+
+@example
+nntp+news.gnus.org:gmane.text.docbook.apps
+@end example
+
+has the tag @samp{DOC-BOOK-APPS:} in the subject of all articles, this
+tag can be removed from the article subjects in the summary buffer for
+the group by putting @code{(gnus-list-identifiers "DOCBOOK-APPS:")}
+into the group parameters for the group.
+
+This can also be used as a group-specific hook function. If you want to
+hear a beep when you enter a group, you could put something like
+@code{(dummy-variable (ding))} in the parameters of that group. If
+@code{dummy-variable} has been bound (see above), it will be set to the
+(meaningless) result of the @code{(ding)} form.
+
+Alternatively, since the VARIABLE becomes local to the group, this
+pattern can be used to temporarily change a hook. For example, if the
+following is added to a group parameter
+
+@lisp
+(gnus-summary-prepared-hook
+ (lambda nil (local-set-key "d" (local-key-binding "n"))))
+@end lisp
+
+when the group is entered, the 'd' key will not mark the article as
+expired.
+
+@end table
+
+@vindex gnus-parameters
+Group parameters can be set via the @code{gnus-parameters} variable too.
+But some variables, such as @code{visible}, have no effect (For this
+case see @code{gnus-permanently-visible-groups} as an alternative.).
+For example:
+
+@lisp
+(setq gnus-parameters
+ '(("mail\\..*"
+ (gnus-show-threads nil)
+ (gnus-use-scoring nil)
+ (gnus-summary-line-format
+ "%U%R%z%I%(%[%d:%ub%-23,23f%]%) %s\n")
+ (gcc-self . t)
+ (display . all))
+
+ ("^nnimap:\\(foo.bar\\)$"
+ (to-group . "\\1"))
+
+ ("mail\\.me"
+ (gnus-use-scoring t))
+
+ ("list\\..*"
+ (total-expire . t)
+ (broken-reply-to . t))))
+@end lisp
+
+All clauses that matches the group name will be used, but the last
+setting ``wins''. So if you have two clauses that both match the
+group name, and both set, say @code{display}, the last setting will
+override the first.
+
+Parameters that are strings will be subjected to regexp substitution,
+as the @code{to-group} example shows.
+
+@vindex gnus-parameters-case-fold-search
+By default, whether comparing the group name and one of those regexps
+specified in @code{gnus-parameters} is done in a case-sensitive manner
+or a case-insensitive manner depends on the value of
+@code{case-fold-search} at the time when the comparison is done. The
+value of @code{case-fold-search} is typically @code{t}; it means, for
+example, the element @code{("INBOX\\.FOO" (total-expire . t))} might be
+applied to both the @samp{INBOX.FOO} group and the @samp{INBOX.foo}
+group. If you want to make those regexps always case-sensitive, set the
+value of the @code{gnus-parameters-case-fold-search} variable to
+@code{nil}. Otherwise, set it to @code{t} if you want to compare them
+always in a case-insensitive manner.
+
+You can define different sorting to different groups via
+@code{gnus-parameters}. Here is an example to sort an @acronym{NNTP}
+group by reverse date to see the latest news at the top and an
+@acronym{RSS} group by subject. In this example, the first group is the
+Debian daily news group @code{gmane.linux.debian.user.news} from
+news.gmane.org. The @acronym{RSS} group corresponds to the Debian
+weekly news RSS feed
+@url{http://packages.debian.org/unstable/newpkg_main.en.rdf},
+@xref{RSS}.
+
+@lisp
+(setq
+ gnus-parameters
+ '(("nntp.*gmane\\.debian\\.user\\.news"
+ (gnus-show-threads nil)
+ (gnus-article-sort-functions '((not gnus-article-sort-by-date)))
+ (gnus-use-adaptive-scoring nil)
+ (gnus-use-scoring nil))
+ ("nnrss.*debian"
+ (gnus-show-threads nil)
+ (gnus-article-sort-functions 'gnus-article-sort-by-subject)
+ (gnus-use-adaptive-scoring nil)
+ (gnus-use-scoring t)
+ (gnus-score-find-score-files-function 'gnus-score-find-single)
+ (gnus-summary-line-format "%U%R%z%d %I%(%[ %s %]%)\n"))))
+@end lisp
+
+
+@node Listing Groups
+@section Listing Groups
+@cindex group listing
+
+These commands all list various slices of the groups available.
+
+@table @kbd
+
+@item l
+@itemx A s
+@kindex A s (Group)
+@kindex l (Group)
+@findex gnus-group-list-groups
+List all groups that have unread articles
+(@code{gnus-group-list-groups}). If the numeric prefix is used, this
+command will list only groups of level ARG and lower. By default, it
+only lists groups of level five (i.e.,
+@code{gnus-group-default-list-level}) or lower (i.e., just subscribed
+groups).
+
+@item L
+@itemx A u
+@kindex A u (Group)
+@kindex L (Group)
+@findex gnus-group-list-all-groups
+List all groups, whether they have unread articles or not
+(@code{gnus-group-list-all-groups}). If the numeric prefix is used,
+this command will list only groups of level ARG and lower. By default,
+it lists groups of level seven or lower (i.e., just subscribed and
+unsubscribed groups).
+
+@item A l
+@kindex A l (Group)
+@findex gnus-group-list-level
+List all unread groups on a specific level
+(@code{gnus-group-list-level}). If given a prefix, also list the groups
+with no unread articles.
+
+@item A k
+@kindex A k (Group)
+@findex gnus-group-list-killed
+List all killed groups (@code{gnus-group-list-killed}). If given a
+prefix argument, really list all groups that are available, but aren't
+currently (un)subscribed. This could entail reading the active file
+from the server.
+
+@item A z
+@kindex A z (Group)
+@findex gnus-group-list-zombies
+List all zombie groups (@code{gnus-group-list-zombies}).
+
+@item A m
+@kindex A m (Group)
+@findex gnus-group-list-matching
+List all unread, subscribed groups with names that match a regexp
+(@code{gnus-group-list-matching}).
+
+@item A M
+@kindex A M (Group)
+@findex gnus-group-list-all-matching
+List groups that match a regexp (@code{gnus-group-list-all-matching}).
+
+@item A A
+@kindex A A (Group)
+@findex gnus-group-list-active
+List absolutely all groups in the active file(s) of the
+server(s) you are connected to (@code{gnus-group-list-active}). This
+might very well take quite a while. It might actually be a better idea
+to do a @kbd{A M} to list all matching, and just give @samp{.} as the
+thing to match on. Also note that this command may list groups that
+don't exist (yet)---these will be listed as if they were killed groups.
+Take the output with some grains of salt.
+
+@item A a
+@kindex A a (Group)
+@findex gnus-group-apropos
+List all groups that have names that match a regexp
+(@code{gnus-group-apropos}).
+
+@item A d
+@kindex A d (Group)
+@findex gnus-group-description-apropos
+List all groups that have names or descriptions that match a regexp
+(@code{gnus-group-description-apropos}).
+
+@item A c
+@kindex A c (Group)
+@findex gnus-group-list-cached
+List all groups with cached articles (@code{gnus-group-list-cached}).
+
+@item A ?
+@kindex A ? (Group)
+@findex gnus-group-list-dormant
+List all groups with dormant articles (@code{gnus-group-list-dormant}).
+
+@item A !
+@kindex A ! (Group)
+@findex gnus-group-list-ticked
+List all groups with ticked articles (@code{gnus-group-list-ticked}).
+
+@item A /
+@kindex A / (Group)
+@findex gnus-group-list-limit
+Further limit groups within the current selection
+(@code{gnus-group-list-limit}). If you've first limited to groups
+with dormant articles with @kbd{A ?}, you can then further limit with
+@kbd{A / c}, which will then limit to groups with cached articles,
+giving you the groups that have both dormant articles and cached
+articles.
+
+@item A f
+@kindex A f (Group)
+@findex gnus-group-list-flush
+Flush groups from the current selection (@code{gnus-group-list-flush}).
+
+@item A p
+@kindex A p (Group)
+@findex gnus-group-list-plus
+List groups plus the current selection (@code{gnus-group-list-plus}).
+
+@end table
+
+@vindex gnus-permanently-visible-groups
+@cindex visible group parameter
+Groups that match the @code{gnus-permanently-visible-groups} regexp will
+always be shown, whether they have unread articles or not. You can also
+add the @code{visible} element to the group parameters in question to
+get the same effect.
+
+@vindex gnus-list-groups-with-ticked-articles
+Groups that have just ticked articles in it are normally listed in the
+group buffer. If @code{gnus-list-groups-with-ticked-articles} is
+@code{nil}, these groups will be treated just like totally empty
+groups. It is @code{t} by default.
+
+
+@node Sorting Groups
+@section Sorting Groups
+@cindex sorting groups
+
+@kindex C-c C-s (Group)
+@findex gnus-group-sort-groups
+@vindex gnus-group-sort-function
+The @kbd{C-c C-s} (@code{gnus-group-sort-groups}) command sorts the
+group buffer according to the function(s) given by the
+@code{gnus-group-sort-function} variable. Available sorting functions
+include:
+
+@table @code
+
+@item gnus-group-sort-by-alphabet
+@findex gnus-group-sort-by-alphabet
+Sort the group names alphabetically. This is the default.
+
+@item gnus-group-sort-by-real-name
+@findex gnus-group-sort-by-real-name
+Sort the group alphabetically on the real (unprefixed) group names.
+
+@item gnus-group-sort-by-level
+@findex gnus-group-sort-by-level
+Sort by group level.
+
+@item gnus-group-sort-by-score
+@findex gnus-group-sort-by-score
+Sort by group score. @xref{Group Score}.
+
+@item gnus-group-sort-by-rank
+@findex gnus-group-sort-by-rank
+Sort by group score and then the group level. The level and the score
+are, when taken together, the group's @dfn{rank}. @xref{Group Score}.
+
+@item gnus-group-sort-by-unread
+@findex gnus-group-sort-by-unread
+Sort by number of unread articles.
+
+@item gnus-group-sort-by-method
+@findex gnus-group-sort-by-method
+Sort alphabetically on the select method.
+
+@item gnus-group-sort-by-server
+@findex gnus-group-sort-by-server
+Sort alphabetically on the Gnus server name.
+
+
+@end table
+
+@code{gnus-group-sort-function} can also be a list of sorting
+functions. In that case, the most significant sort key function must be
+the last one.
+
+
+There are also a number of commands for sorting directly according to
+some sorting criteria:
+
+@table @kbd
+@item G S a
+@kindex G S a (Group)
+@findex gnus-group-sort-groups-by-alphabet
+Sort the group buffer alphabetically by group name
+(@code{gnus-group-sort-groups-by-alphabet}).
+
+@item G S u
+@kindex G S u (Group)
+@findex gnus-group-sort-groups-by-unread
+Sort the group buffer by the number of unread articles
+(@code{gnus-group-sort-groups-by-unread}).
+
+@item G S l
+@kindex G S l (Group)
+@findex gnus-group-sort-groups-by-level
+Sort the group buffer by group level
+(@code{gnus-group-sort-groups-by-level}).
+
+@item G S v
+@kindex G S v (Group)
+@findex gnus-group-sort-groups-by-score
+Sort the group buffer by group score
+(@code{gnus-group-sort-groups-by-score}). @xref{Group Score}.
+
+@item G S r
+@kindex G S r (Group)
+@findex gnus-group-sort-groups-by-rank
+Sort the group buffer by group rank
+(@code{gnus-group-sort-groups-by-rank}). @xref{Group Score}.
+
+@item G S m
+@kindex G S m (Group)
+@findex gnus-group-sort-groups-by-method
+Sort the group buffer alphabetically by back end name@*
+(@code{gnus-group-sort-groups-by-method}).
+
+@item G S n
+@kindex G S n (Group)
+@findex gnus-group-sort-groups-by-real-name
+Sort the group buffer alphabetically by real (unprefixed) group name
+(@code{gnus-group-sort-groups-by-real-name}).
+
+@end table
+
+All the commands below obey the process/prefix convention
+(@pxref{Process/Prefix}).
+
+When given a symbolic prefix (@pxref{Symbolic Prefixes}), all these
+commands will sort in reverse order.
+
+You can also sort a subset of the groups:
+
+@table @kbd
+@item G P a
+@kindex G P a (Group)
+@findex gnus-group-sort-selected-groups-by-alphabet
+Sort the groups alphabetically by group name
+(@code{gnus-group-sort-selected-groups-by-alphabet}).
+
+@item G P u
+@kindex G P u (Group)
+@findex gnus-group-sort-selected-groups-by-unread
+Sort the groups by the number of unread articles
+(@code{gnus-group-sort-selected-groups-by-unread}).
+
+@item G P l
+@kindex G P l (Group)
+@findex gnus-group-sort-selected-groups-by-level
+Sort the groups by group level
+(@code{gnus-group-sort-selected-groups-by-level}).
+
+@item G P v
+@kindex G P v (Group)
+@findex gnus-group-sort-selected-groups-by-score
+Sort the groups by group score
+(@code{gnus-group-sort-selected-groups-by-score}). @xref{Group Score}.
+
+@item G P r
+@kindex G P r (Group)
+@findex gnus-group-sort-selected-groups-by-rank
+Sort the groups by group rank
+(@code{gnus-group-sort-selected-groups-by-rank}). @xref{Group Score}.
+
+@item G P m
+@kindex G P m (Group)
+@findex gnus-group-sort-selected-groups-by-method
+Sort the groups alphabetically by back end name@*
+(@code{gnus-group-sort-selected-groups-by-method}).
+
+@item G P n
+@kindex G P n (Group)
+@findex gnus-group-sort-selected-groups-by-real-name
+Sort the groups alphabetically by real (unprefixed) group name
+(@code{gnus-group-sort-selected-groups-by-real-name}).
+
+@item G P s
+@kindex G P s (Group)
+@findex gnus-group-sort-selected-groups
+Sort the groups according to @code{gnus-group-sort-function}.
+
+@end table
+
+And finally, note that you can use @kbd{C-k} and @kbd{C-y} to manually
+move groups around.
+
+
+@node Group Maintenance
+@section Group Maintenance
+@cindex bogus groups
+
+@table @kbd
+@item b
+@kindex b (Group)
+@findex gnus-group-check-bogus-groups
+Find bogus groups and delete them
+(@code{gnus-group-check-bogus-groups}).
+
+@item F
+@kindex F (Group)
+@findex gnus-group-find-new-groups
+Find new groups and process them (@code{gnus-group-find-new-groups}).
+With 1 @kbd{C-u}, use the @code{ask-server} method to query the server
+for new groups. With 2 @kbd{C-u}'s, use most complete method possible
+to query the server for new groups, and subscribe the new groups as
+zombies.
+
+@item C-c C-x
+@kindex C-c C-x (Group)
+@findex gnus-group-expire-articles
+@cindex expiring mail
+Run all expirable articles in the current group through the expiry
+process (if any) (@code{gnus-group-expire-articles}). That is, delete
+all expirable articles in the group that have been around for a while.
+(@pxref{Expiring Mail}).
+
+@item C-c C-M-x
+@kindex C-c C-M-x (Group)
+@findex gnus-group-expire-all-groups
+@cindex expiring mail
+Run all expirable articles in all groups through the expiry process
+(@code{gnus-group-expire-all-groups}).
+
+@end table
+
+
+@node Browse Foreign Server
+@section Browse Foreign Server
+@cindex foreign servers
+@cindex browsing servers
+
+@table @kbd
+@item B
+@kindex B (Group)
+@findex gnus-group-browse-foreign-server
+You will be queried for a select method and a server name. Gnus will
+then attempt to contact this server and let you browse the groups there
+(@code{gnus-group-browse-foreign-server}).
+@end table
+
+@findex gnus-browse-mode
+A new buffer with a list of available groups will appear. This buffer
+will use the @code{gnus-browse-mode}. This buffer looks a bit (well,
+a lot) like a normal group buffer.
+
+Here's a list of keystrokes available in the browse mode:
+
+@table @kbd
+@item n
+@kindex n (Browse)
+@findex gnus-group-next-group
+Go to the next group (@code{gnus-group-next-group}).
+
+@item p
+@kindex p (Browse)
+@findex gnus-group-prev-group
+Go to the previous group (@code{gnus-group-prev-group}).
+
+@item SPACE
+@kindex SPACE (Browse)
+@findex gnus-browse-read-group
+Enter the current group and display the first article
+(@code{gnus-browse-read-group}).
+
+@item RET
+@kindex RET (Browse)
+@findex gnus-browse-select-group
+Enter the current group (@code{gnus-browse-select-group}).
+
+@item u
+@kindex u (Browse)
+@findex gnus-browse-unsubscribe-current-group
+@vindex gnus-browse-subscribe-newsgroup-method
+Unsubscribe to the current group, or, as will be the case here,
+subscribe to it (@code{gnus-browse-unsubscribe-current-group}). You
+can affect the way the new group is entered into the Group buffer
+using the variable @code{gnus-browse-subscribe-newsgroup-method}. See
+@pxref{Subscription Methods} for available options.
+
+@item l
+@itemx q
+@kindex q (Browse)
+@kindex l (Browse)
+@findex gnus-browse-exit
+Exit browse mode (@code{gnus-browse-exit}).
+
+@item d
+@kindex d (Browse)
+@findex gnus-browse-describe-group
+Describe the current group (@code{gnus-browse-describe-group}).
+
+@item ?
+@kindex ? (Browse)
+@findex gnus-browse-describe-briefly
+Describe browse mode briefly (well, there's not much to describe, is
+there) (@code{gnus-browse-describe-briefly}).
+
+@item DEL
+@kindex DEL (Browse)
+@findex gnus-browse-delete-group
+This function will delete the current group
+(@code{gnus-browse-delete-group}). If given a prefix, this function
+will actually delete all the articles in the group, and forcibly
+remove the group itself from the face of the Earth. Use a prefix only
+if you are absolutely sure of what you are doing.
+@end table
+
+
+@node Exiting Gnus
+@section Exiting Gnus
+@cindex exiting Gnus
+
+Yes, Gnus is ex(c)iting.
+
+@table @kbd
+@item z
+@kindex z (Group)
+@findex gnus-group-suspend
+Suspend Gnus (@code{gnus-group-suspend}). This doesn't really exit Gnus,
+but it kills all buffers except the Group buffer. I'm not sure why this
+is a gain, but then who am I to judge?
+
+@item q
+@kindex q (Group)
+@findex gnus-group-exit
+@c @icon{gnus-group-exit}
+Quit Gnus (@code{gnus-group-exit}).
+
+@item Q
+@kindex Q (Group)
+@findex gnus-group-quit
+Quit Gnus without saving the @file{.newsrc} files (@code{gnus-group-quit}).
+The dribble file will be saved, though (@pxref{Auto Save}).
+@end table
+
+@vindex gnus-exit-gnus-hook
+@vindex gnus-suspend-gnus-hook
+@vindex gnus-after-exiting-gnus-hook
+@code{gnus-suspend-gnus-hook} is called when you suspend Gnus and
+@code{gnus-exit-gnus-hook} is called when you quit Gnus, while
+@code{gnus-after-exiting-gnus-hook} is called as the final item when
+exiting Gnus.
+
+Note:
+
+@quotation
+Miss Lisa Cannifax, while sitting in English class, felt her feet go
+numbly heavy and herself fall into a hazy trance as the boy sitting
+behind her drew repeated lines with his pencil across the back of her
+plastic chair.
+@end quotation
+
+
+@node Group Topics
+@section Group Topics
+@cindex topics
+
+If you read lots and lots of groups, it might be convenient to group
+them hierarchically according to topics. You put your Emacs groups over
+here, your sex groups over there, and the rest (what, two groups or so?)
+you put in some misc section that you never bother with anyway. You can
+even group the Emacs sex groups as a sub-topic to either the Emacs
+groups or the sex groups---or both! Go wild!
+
+@iftex
+@iflatex
+\gnusfigure{Group Topics}{400}{
+\put(75,50){\epsfig{figure=ps/group-topic,height=9cm}}
+}
+@end iflatex
+@end iftex
+
+Here's an example:
+
+@example
+Gnus
+ Emacs -- I wuw it!
+ 3: comp.emacs
+ 2: alt.religion.emacs
+ Naughty Emacs
+ 452: alt.sex.emacs
+ 0: comp.talk.emacs.recovery
+ Misc
+ 8: comp.binaries.fractals
+ 13: comp.sources.unix
+@end example
+
+@findex gnus-topic-mode
+@kindex t (Group)
+To get this @emph{fab} functionality you simply turn on (ooh!) the
+@code{gnus-topic} minor mode---type @kbd{t} in the group buffer. (This
+is a toggling command.)
+
+Go ahead, just try it. I'll still be here when you get back. La de
+dum@dots{} Nice tune, that@dots{} la la la@dots{} What, you're back?
+Yes, and now press @kbd{l}. There. All your groups are now listed
+under @samp{misc}. Doesn't that make you feel all warm and fuzzy?
+Hot and bothered?
+
+If you want this permanently enabled, you should add that minor mode to
+the hook for the group mode. Put the following line in your
+@file{~/.gnus.el} file:
+
+@lisp
+(add-hook 'gnus-group-mode-hook 'gnus-topic-mode)
+@end lisp
+
+@menu
+* Topic Commands:: Interactive E-Z commands.
+* Topic Variables:: How to customize the topics the Lisp Way.
+* Topic Sorting:: Sorting each topic individually.
+* Topic Topology:: A map of the world.
+* Topic Parameters:: Parameters that apply to all groups in a topic.
+@end menu
+
+
+@node Topic Commands
+@subsection Topic Commands
+@cindex topic commands
+
+When the topic minor mode is turned on, a new @kbd{T} submap will be
+available. In addition, a few of the standard keys change their
+definitions slightly.
+
+In general, the following kinds of operations are possible on topics.
+First of all, you want to create topics. Secondly, you want to put
+groups in topics and to move them around until you have an order you
+like. The third kind of operation is to show/hide parts of the whole
+shebang. You might want to hide a topic including its subtopics and
+groups, to get a better overview of the other groups.
+
+Here is a list of the basic keys that you might need to set up topics
+the way you like.
+
+@table @kbd
+
+@item T n
+@kindex T n (Topic)
+@findex gnus-topic-create-topic
+Prompt for a new topic name and create it
+(@code{gnus-topic-create-topic}).
+
+@item T TAB
+@itemx TAB
+@kindex T TAB (Topic)
+@kindex TAB (Topic)
+@findex gnus-topic-indent
+``Indent'' the current topic so that it becomes a sub-topic of the
+previous topic (@code{gnus-topic-indent}). If given a prefix,
+``un-indent'' the topic instead.
+
+@item M-TAB
+@kindex M-TAB (Topic)
+@findex gnus-topic-unindent
+``Un-indent'' the current topic so that it becomes a sub-topic of the
+parent of its current parent (@code{gnus-topic-unindent}).
+
+@end table
+
+The following two keys can be used to move groups and topics around.
+They work like the well-known cut and paste. @kbd{C-k} is like cut and
+@kbd{C-y} is like paste. Of course, this being Emacs, we use the terms
+kill and yank rather than cut and paste.
+
+@table @kbd
+
+@item C-k
+@kindex C-k (Topic)
+@findex gnus-topic-kill-group
+Kill a group or topic (@code{gnus-topic-kill-group}). All groups in the
+topic will be removed along with the topic.
+
+@item C-y
+@kindex C-y (Topic)
+@findex gnus-topic-yank-group
+Yank the previously killed group or topic
+(@code{gnus-topic-yank-group}). Note that all topics will be yanked
+before all groups.
+
+So, to move a topic to the beginning of the list of topics, just hit
+@kbd{C-k} on it. This is like the ``cut'' part of cut and paste. Then,
+move the cursor to the beginning of the buffer (just below the ``Gnus''
+topic) and hit @kbd{C-y}. This is like the ``paste'' part of cut and
+paste. Like I said---E-Z.
+
+You can use @kbd{C-k} and @kbd{C-y} on groups as well as on topics. So
+you can move topics around as well as groups.
+
+@end table
+
+After setting up the topics the way you like them, you might wish to
+hide a topic, or to show it again. That's why we have the following
+key.
+
+@table @kbd
+
+@item RET
+@kindex RET (Topic)
+@findex gnus-topic-select-group
+@itemx SPACE
+Either select a group or fold a topic (@code{gnus-topic-select-group}).
+When you perform this command on a group, you'll enter the group, as
+usual. When done on a topic line, the topic will be folded (if it was
+visible) or unfolded (if it was folded already). So it's basically a
+toggling command on topics. In addition, if you give a numerical
+prefix, group on that level (and lower) will be displayed.
+
+@end table
+
+Now for a list of other commands, in no particular order.
+
+@table @kbd
+
+@item T m
+@kindex T m (Topic)
+@findex gnus-topic-move-group
+Move the current group to some other topic
+(@code{gnus-topic-move-group}). This command uses the process/prefix
+convention (@pxref{Process/Prefix}).
+
+@item T j
+@kindex T j (Topic)
+@findex gnus-topic-jump-to-topic
+Go to a topic (@code{gnus-topic-jump-to-topic}).
+
+@item T c
+@kindex T c (Topic)
+@findex gnus-topic-copy-group
+Copy the current group to some other topic
+(@code{gnus-topic-copy-group}). This command uses the process/prefix
+convention (@pxref{Process/Prefix}).
+
+@item T h
+@kindex T h (Topic)
+@findex gnus-topic-hide-topic
+Hide the current topic (@code{gnus-topic-hide-topic}). If given
+a prefix, hide the topic permanently.
+
+@item T s
+@kindex T s (Topic)
+@findex gnus-topic-show-topic
+Show the current topic (@code{gnus-topic-show-topic}). If given
+a prefix, show the topic permanently.
+
+@item T D
+@kindex T D (Topic)
+@findex gnus-topic-remove-group
+Remove a group from the current topic (@code{gnus-topic-remove-group}).
+This command is mainly useful if you have the same group in several
+topics and wish to remove it from one of the topics. You may also
+remove a group from all topics, but in that case, Gnus will add it to
+the root topic the next time you start Gnus. In fact, all new groups
+(which, naturally, don't belong to any topic) will show up in the root
+topic.
+
+This command uses the process/prefix convention
+(@pxref{Process/Prefix}).
+
+@item T M
+@kindex T M (Topic)
+@findex gnus-topic-move-matching
+Move all groups that match some regular expression to a topic
+(@code{gnus-topic-move-matching}).
+
+@item T C
+@kindex T C (Topic)
+@findex gnus-topic-copy-matching
+Copy all groups that match some regular expression to a topic
+(@code{gnus-topic-copy-matching}).
+
+@item T H
+@kindex T H (Topic)
+@findex gnus-topic-toggle-display-empty-topics
+Toggle hiding empty topics
+(@code{gnus-topic-toggle-display-empty-topics}).
+
+@item T #
+@kindex T # (Topic)
+@findex gnus-topic-mark-topic
+Mark all groups in the current topic with the process mark
+(@code{gnus-topic-mark-topic}). This command works recursively on
+sub-topics unless given a prefix.
+
+@item T M-#
+@kindex T M-# (Topic)
+@findex gnus-topic-unmark-topic
+Remove the process mark from all groups in the current topic
+(@code{gnus-topic-unmark-topic}). This command works recursively on
+sub-topics unless given a prefix.
+
+@item C-c C-x
+@kindex C-c C-x (Topic)
+@findex gnus-topic-expire-articles
+@cindex expiring mail
+Run all expirable articles in the current group or topic through the
+expiry process (if any)
+(@code{gnus-topic-expire-articles}). (@pxref{Expiring Mail}).
+
+@item T r
+@kindex T r (Topic)
+@findex gnus-topic-rename
+Rename a topic (@code{gnus-topic-rename}).
+
+@item T DEL
+@kindex T DEL (Topic)
+@findex gnus-topic-delete
+Delete an empty topic (@code{gnus-topic-delete}).
+
+@item A T
+@kindex A T (Topic)
+@findex gnus-topic-list-active
+List all groups that Gnus knows about in a topics-ified way
+(@code{gnus-topic-list-active}).
+
+@item T M-n
+@kindex T M-n (Topic)
+@findex gnus-topic-goto-next-topic
+Go to the next topic (@code{gnus-topic-goto-next-topic}).
+
+@item T M-p
+@kindex T M-p (Topic)
+@findex gnus-topic-goto-previous-topic
+Go to the previous topic (@code{gnus-topic-goto-previous-topic}).
+
+@item G p
+@kindex G p (Topic)
+@findex gnus-topic-edit-parameters
+@cindex group parameters
+@cindex topic parameters
+@cindex parameters
+Edit the topic parameters (@code{gnus-topic-edit-parameters}).
+@xref{Topic Parameters}.
+
+@end table
+
+
+@node Topic Variables
+@subsection Topic Variables
+@cindex topic variables
+
+The previous section told you how to tell Gnus which topics to display.
+This section explains how to tell Gnus what to display about each topic.
+
+@vindex gnus-topic-line-format
+The topic lines themselves are created according to the
+@code{gnus-topic-line-format} variable (@pxref{Formatting Variables}).
+Valid elements are:
+
+@table @samp
+@item i
+Indentation.
+@item n
+Topic name.
+@item v
+Visibility.
+@item l
+Level.
+@item g
+Number of groups in the topic.
+@item a
+Number of unread articles in the topic.
+@item A
+Number of unread articles in the topic and all its subtopics.
+@end table
+
+@vindex gnus-topic-indent-level
+Each sub-topic (and the groups in the sub-topics) will be indented with
+@code{gnus-topic-indent-level} times the topic level number of spaces.
+The default is 2.
+
+@vindex gnus-topic-mode-hook
+@code{gnus-topic-mode-hook} is called in topic minor mode buffers.
+
+@vindex gnus-topic-display-empty-topics
+The @code{gnus-topic-display-empty-topics} says whether to display even
+topics that have no unread articles in them. The default is @code{t}.
+
+
+@node Topic Sorting
+@subsection Topic Sorting
+@cindex topic sorting
+
+You can sort the groups in each topic individually with the following
+commands:
+
+
+@table @kbd
+@item T S a
+@kindex T S a (Topic)
+@findex gnus-topic-sort-groups-by-alphabet
+Sort the current topic alphabetically by group name
+(@code{gnus-topic-sort-groups-by-alphabet}).
+
+@item T S u
+@kindex T S u (Topic)
+@findex gnus-topic-sort-groups-by-unread
+Sort the current topic by the number of unread articles
+(@code{gnus-topic-sort-groups-by-unread}).
+
+@item T S l
+@kindex T S l (Topic)
+@findex gnus-topic-sort-groups-by-level
+Sort the current topic by group level
+(@code{gnus-topic-sort-groups-by-level}).
+
+@item T S v
+@kindex T S v (Topic)
+@findex gnus-topic-sort-groups-by-score
+Sort the current topic by group score
+(@code{gnus-topic-sort-groups-by-score}). @xref{Group Score}.
+
+@item T S r
+@kindex T S r (Topic)
+@findex gnus-topic-sort-groups-by-rank
+Sort the current topic by group rank
+(@code{gnus-topic-sort-groups-by-rank}). @xref{Group Score}.
+
+@item T S m
+@kindex T S m (Topic)
+@findex gnus-topic-sort-groups-by-method
+Sort the current topic alphabetically by back end name
+(@code{gnus-topic-sort-groups-by-method}).
+
+@item T S e
+@kindex T S e (Topic)
+@findex gnus-topic-sort-groups-by-server
+Sort the current topic alphabetically by server name
+(@code{gnus-topic-sort-groups-by-server}).
+
+@item T S s
+@kindex T S s (Topic)
+@findex gnus-topic-sort-groups
+Sort the current topic according to the function(s) given by the
+@code{gnus-group-sort-function} variable
+(@code{gnus-topic-sort-groups}).
+
+@end table
+
+When given a prefix argument, all these commands will sort in reverse
+order. @xref{Sorting Groups}, for more information about group
+sorting.
+
+
+@node Topic Topology
+@subsection Topic Topology
+@cindex topic topology
+@cindex topology
+
+So, let's have a look at an example group buffer:
+
+@example
+@group
+Gnus
+ Emacs -- I wuw it!
+ 3: comp.emacs
+ 2: alt.religion.emacs
+ Naughty Emacs
+ 452: alt.sex.emacs
+ 0: comp.talk.emacs.recovery
+ Misc
+ 8: comp.binaries.fractals
+ 13: comp.sources.unix
+@end group
+@end example
+
+So, here we have one top-level topic (@samp{Gnus}), two topics under
+that, and one sub-topic under one of the sub-topics. (There is always
+just one (1) top-level topic). This topology can be expressed as
+follows:
+
+@lisp
+(("Gnus" visible)
+ (("Emacs -- I wuw it!" visible)
+ (("Naughty Emacs" visible)))
+ (("Misc" visible)))
+@end lisp
+
+@vindex gnus-topic-topology
+This is in fact how the variable @code{gnus-topic-topology} would look
+for the display above. That variable is saved in the @file{.newsrc.eld}
+file, and shouldn't be messed with manually---unless you really want
+to. Since this variable is read from the @file{.newsrc.eld} file,
+setting it in any other startup files will have no effect.
+
+This topology shows what topics are sub-topics of what topics (right),
+and which topics are visible. Two settings are currently
+allowed---@code{visible} and @code{invisible}.
+
+
+@node Topic Parameters
+@subsection Topic Parameters
+@cindex topic parameters
+
+All groups in a topic will inherit group parameters from the parent
+(and ancestor) topic parameters. All valid group parameters are valid
+topic parameters (@pxref{Group Parameters}). When the agent is
+enabled, all agent parameters (See Agent Parameters in @ref{Category
+Syntax}) are also valid topic parameters.
+
+In addition, the following parameters are only valid as topic
+parameters:
+
+@table @code
+@item subscribe
+When subscribing new groups by topic (@pxref{Subscription Methods}), the
+@code{subscribe} topic parameter says what groups go in what topic. Its
+value should be a regexp to match the groups that should go in that
+topic.
+
+@item subscribe-level
+When subscribing new groups by topic (see the @code{subscribe} parameter),
+the group will be subscribed with the level specified in the
+@code{subscribe-level} instead of @code{gnus-level-default-subscribed}.
+
+@end table
+
+Group parameters (of course) override topic parameters, and topic
+parameters in sub-topics override topic parameters in super-topics. You
+know. Normal inheritance rules. (@dfn{Rules} is here a noun, not a
+verb, although you may feel free to disagree with me here.)
+
+@example
+@group
+Gnus
+ Emacs
+ 3: comp.emacs
+ 2: alt.religion.emacs
+ 452: alt.sex.emacs
+ Relief
+ 452: alt.sex.emacs
+ 0: comp.talk.emacs.recovery
+ Misc
+ 8: comp.binaries.fractals
+ 13: comp.sources.unix
+ 452: alt.sex.emacs
+@end group
+@end example
+
+The @samp{Emacs} topic has the topic parameter @code{(score-file
+. "emacs.SCORE")}; the @samp{Relief} topic has the topic parameter
+@code{(score-file . "relief.SCORE")}; and the @samp{Misc} topic has the
+topic parameter @code{(score-file . "emacs.SCORE")}. In addition,
+@* @samp{alt.religion.emacs} has the group parameter @code{(score-file
+. "religion.SCORE")}.
+
+Now, when you enter @samp{alt.sex.emacs} in the @samp{Relief} topic, you
+will get the @file{relief.SCORE} home score file. If you enter the same
+group in the @samp{Emacs} topic, you'll get the @file{emacs.SCORE} home
+score file. If you enter the group @samp{alt.religion.emacs}, you'll
+get the @file{religion.SCORE} home score file.
+
+This seems rather simple and self-evident, doesn't it? Well, yes. But
+there are some problems, especially with the @code{total-expiry}
+parameter. Say you have a mail group in two topics; one with
+@code{total-expiry} and one without. What happens when you do @kbd{M-x
+gnus-expire-all-expirable-groups}? Gnus has no way of telling which one
+of these topics you mean to expire articles from, so anything may
+happen. In fact, I hereby declare that it is @dfn{undefined} what
+happens. You just have to be careful if you do stuff like that.
+
+
+@node Non-ASCII Group Names
+@section Accessing groups of non-English names
+@cindex non-ascii group names
+
+There are some news servers that provide groups of which the names are
+expressed with their native languages in the world. For instance, in a
+certain news server there are some newsgroups of which the names are
+spelled in Chinese, where people are talking in Chinese. You can, of
+course, subscribe to such news groups using Gnus. Currently Gnus
+supports non-@acronym{ASCII} group names not only with the @code{nntp}
+back end but also with the @code{nnml} back end and the @code{nnrss}
+back end.
+
+Every such group name is encoded by a certain charset in the server
+side (in an @acronym{NNTP} server its administrator determines the
+charset, but for groups in the other back ends it is determined by you).
+Gnus has to display the decoded ones for you in the group buffer and the
+article buffer, and needs to use the encoded ones when communicating
+with servers. However, Gnus doesn't know what charset is used for each
+non-@acronym{ASCII} group name. The following two variables are just
+the ones for telling Gnus what charset should be used for each group:
+
+@table @code
+@item gnus-group-name-charset-method-alist
+@vindex gnus-group-name-charset-method-alist
+An alist of select methods and charsets. The default value is
+@code{nil}. The names of groups in the server specified by that select
+method are all supposed to use the corresponding charset. For example:
+
+@lisp
+(setq gnus-group-name-charset-method-alist
+ '(((nntp "news.com.cn") . cn-gb-2312)))
+@end lisp
+
+Charsets specified for groups with this variable are preferred to the
+ones specified for the same groups with the
+@code{gnus-group-name-charset-group-alist} variable (see below).
+
+A select method can be very long, like:
+
+@lisp
+(nntp "gmane"
+ (nntp-address "news.gmane.org")
+ (nntp-end-of-line "\n")
+ (nntp-open-connection-function
+ nntp-open-via-rlogin-and-telnet)
+ (nntp-via-rlogin-command "ssh")
+ (nntp-via-rlogin-command-switches
+ ("-C" "-t" "-e" "none"))
+ (nntp-via-address @dots{}))
+@end lisp
+
+In that case, you can truncate it into @code{(nntp "gmane")} in this
+variable. That is, it is enough to contain only the back end name and
+the server name.
+
+@item gnus-group-name-charset-group-alist
+@cindex UTF-8 group names
+@vindex gnus-group-name-charset-group-alist
+An alist of regexp of group name and the charset for group names.
+@code{((".*" . utf-8))} is the default value if UTF-8 is supported,
+otherwise the default is @code{nil}. For example:
+
+@lisp
+(setq gnus-group-name-charset-group-alist
+ '(("\\.com\\.cn:" . cn-gb-2312)
+ (".*" . utf-8)))
+@end lisp
+
+Note that this variable is ignored if the match is made with
+@code{gnus-group-name-charset-method-alist}.
+@end table
+
+Those two variables are used also to determine the charset for encoding
+and decoding non-@acronym{ASCII} group names that are in the back ends
+other than @code{nntp}. It means that it is you who determine it. If
+you do nothing, the charset used for group names in those back ends will
+all be @code{utf-8} because of the last element of
+@code{gnus-group-name-charset-group-alist}.
+
+There is one more important variable for non-@acronym{ASCII} group
+names:
+
+@table @code
+@item nnmail-pathname-coding-system
+@vindex nnmail-pathname-coding-system
+The value of this variable should be a coding system or @code{nil}. The
+default is @code{nil} in Emacs, or is the aliasee of the coding system
+named @code{file-name} (a certain coding system of which an alias is
+@code{file-name}) in XEmacs.
+
+The @code{nnml} back end, the @code{nnrss} back end, the agent, and
+the cache use non-@acronym{ASCII} group names in those files and
+directories. This variable overrides the value of
+@code{file-name-coding-system} which specifies the coding system used
+when encoding and decoding those file names and directory names.
+
+In XEmacs (with the @code{mule} feature), @code{file-name-coding-system}
+is the only means to specify the coding system used to encode and decode
+file names. On the other hand, Emacs uses the value of
+@code{default-file-name-coding-system} if @code{file-name-coding-system}
+is @code{nil} or it is bound to the value of
+@code{nnmail-pathname-coding-system} which is @code{nil}.
+
+Normally the value of @code{default-file-name-coding-system} in Emacs or
+@code{nnmail-pathname-coding-system} in XEmacs is initialized according
+to the locale, so you will need to do nothing if the value is suitable
+to encode and decode non-@acronym{ASCII} group names.
+
+The value of this variable (or @code{default-file-name-coding-system})
+does not necessarily need to be the same value that is determined by
+@code{gnus-group-name-charset-method-alist} and
+@code{gnus-group-name-charset-group-alist}.
+
+If @code{default-file-name-coding-system} or this variable is
+initialized by default to @code{iso-latin-1} for example, although you
+want to subscribe to the groups spelled in Chinese, that is the most
+typical case where you have to customize
+@code{nnmail-pathname-coding-system}. The @code{utf-8} coding system is
+a good candidate for it. Otherwise, you may change the locale in your
+system so that @code{default-file-name-coding-system} or this variable
+may be initialized to an appropriate value.
+@end table
+
+Note that when you copy or move articles from a non-@acronym{ASCII}
+group to another group, the charset used to encode and decode group
+names should be the same in both groups. Otherwise the Newsgroups
+header will be displayed incorrectly in the article buffer.
+
+
+@node Misc Group Stuff
+@section Misc Group Stuff
+
+@menu
+* Scanning New Messages:: Asking Gnus to see whether new messages have arrived.
+* Group Information:: Information and help on groups and Gnus.
+* Group Timestamp:: Making Gnus keep track of when you last read a group.
+* File Commands:: Reading and writing the Gnus files.
+* Sieve Commands:: Managing Sieve scripts.
+@end menu
+
+@table @kbd
+
+@item v
+@kindex v (Group)
+@cindex keys, reserved for users (Group)
+The key @kbd{v} is reserved for users. You can bind it to some
+command or better use it as a prefix key. For example:
+
+@lisp
+(define-key gnus-group-mode-map (kbd "v j d")
+ (lambda ()
+ (interactive)
+ (gnus-group-jump-to-group "nndraft:drafts")))
+@end lisp
+
+On keys reserved for users in Emacs and on keybindings in general
+@xref{Keymaps, Keymaps, , emacs, The Emacs Editor}.
+
+@item ^
+@kindex ^ (Group)
+@findex gnus-group-enter-server-mode
+Enter the server buffer (@code{gnus-group-enter-server-mode}).
+@xref{Server Buffer}.
+
+@item a
+@kindex a (Group)
+@findex gnus-group-post-news
+Start composing a message (a news by default)
+(@code{gnus-group-post-news}). If given a prefix, post to the group
+under the point. If the prefix is 1, prompt for a group to post to.
+Contrary to what the name of this function suggests, the prepared
+article might be a mail instead of a news, if a mail group is specified
+with the prefix argument. @xref{Composing Messages}.
+
+@item m
+@kindex m (Group)
+@findex gnus-group-mail
+Mail a message somewhere (@code{gnus-group-mail}). If given a prefix,
+use the posting style of the group under the point. If the prefix is 1,
+prompt for a group name to find the posting style.
+@xref{Composing Messages}.
+
+@item i
+@kindex i (Group)
+@findex gnus-group-news
+Start composing a news (@code{gnus-group-news}). If given a prefix,
+post to the group under the point. If the prefix is 1, prompt
+for group to post to. @xref{Composing Messages}.
+
+This function actually prepares a news even when using mail groups.
+This is useful for ``posting'' messages to mail groups without actually
+sending them over the network: they're just saved directly to the group
+in question. The corresponding back end must have a request-post method
+for this to work though.
+
+@item G z
+@kindex G z (Group)
+@findex gnus-group-compact-group
+
+Compact the group under point (@code{gnus-group-compact-group}).
+Currently implemented only in nnml (@pxref{Mail Spool}). This removes
+gaps between article numbers, hence getting a correct total article
+count.
+
+@end table
+
+Variables for the group buffer:
+
+@table @code
+
+@item gnus-group-mode-hook
+@vindex gnus-group-mode-hook
+is called after the group buffer has been
+created.
+
+@item gnus-group-prepare-hook
+@vindex gnus-group-prepare-hook
+is called after the group buffer is
+generated. It may be used to modify the buffer in some strange,
+unnatural way.
+
+@item gnus-group-prepared-hook
+@vindex gnus-group-prepare-hook
+is called as the very last thing after the group buffer has been
+generated. It may be used to move point around, for instance.
+
+@item gnus-permanently-visible-groups
+@vindex gnus-permanently-visible-groups
+Groups matching this regexp will always be listed in the group buffer,
+whether they are empty or not.
+
+@end table
+
+@node Scanning New Messages
+@subsection Scanning New Messages
+@cindex new messages
+@cindex scanning new news
+
+@table @kbd
+
+@item g
+@kindex g (Group)
+@findex gnus-group-get-new-news
+@c @icon{gnus-group-get-new-news}
+Check the server(s) for new articles. If the numerical prefix is used,
+this command will check only groups of level @var{arg} and lower
+(@code{gnus-group-get-new-news}). If given a non-numerical prefix, this
+command will force a total re-reading of the active file(s) from the
+back end(s).
+
+@item M-g
+@kindex M-g (Group)
+@findex gnus-group-get-new-news-this-group
+@vindex gnus-goto-next-group-when-activating
+@c @icon{gnus-group-get-new-news-this-group}
+Check whether new articles have arrived in the current group
+(@code{gnus-group-get-new-news-this-group}).
+@code{gnus-goto-next-group-when-activating} says whether this command is
+to move point to the next group or not. It is @code{t} by default.
+
+@findex gnus-activate-all-groups
+@cindex activating groups
+@item C-c M-g
+@kindex C-c M-g (Group)
+Activate absolutely all groups (@code{gnus-activate-all-groups}).
+
+@item R
+@kindex R (Group)
+@cindex restarting
+@findex gnus-group-restart
+Restart Gnus (@code{gnus-group-restart}). This saves the @file{.newsrc}
+file(s), closes the connection to all servers, clears up all run-time
+Gnus variables, and then starts Gnus all over again.
+
+@end table
+
+@vindex gnus-get-new-news-hook
+@code{gnus-get-new-news-hook} is run just before checking for new news.
+
+@vindex gnus-after-getting-new-news-hook
+@code{gnus-after-getting-new-news-hook} is run after checking for new
+news.
+
+
+@node Group Information
+@subsection Group Information
+@cindex group information
+@cindex information on groups
+
+@table @kbd
+
+
+@item H d
+@itemx C-c C-d
+@c @icon{gnus-group-describe-group}
+@kindex H d (Group)
+@kindex C-c C-d (Group)
+@cindex describing groups
+@cindex group description
+@findex gnus-group-describe-group
+Describe the current group (@code{gnus-group-describe-group}). If given
+a prefix, force Gnus to re-read the description from the server.
+
+@item M-d
+@kindex M-d (Group)
+@findex gnus-group-describe-all-groups
+Describe all groups (@code{gnus-group-describe-all-groups}). If given a
+prefix, force Gnus to re-read the description file from the server.
+
+@item H v
+@itemx V
+@kindex V (Group)
+@kindex H v (Group)
+@cindex version
+@findex gnus-version
+Display current Gnus version numbers (@code{gnus-version}).
+
+@item ?
+@kindex ? (Group)
+@findex gnus-group-describe-briefly
+Give a very short help message (@code{gnus-group-describe-briefly}).
+
+@item C-c C-i
+@kindex C-c C-i (Group)
+@cindex info
+@cindex manual
+@findex gnus-info-find-node
+Go to the Gnus info node (@code{gnus-info-find-node}).
+@end table
+
+
+@node Group Timestamp
+@subsection Group Timestamp
+@cindex timestamps
+@cindex group timestamps
+
+It can be convenient to let Gnus keep track of when you last read a
+group. To set the ball rolling, you should add
+@code{gnus-group-set-timestamp} to @code{gnus-select-group-hook}:
+
+@lisp
+(add-hook 'gnus-select-group-hook 'gnus-group-set-timestamp)
+@end lisp
+
+After doing this, each time you enter a group, it'll be recorded.
+
+This information can be displayed in various ways---the easiest is to
+use the @samp{%d} spec in the group line format:
+
+@lisp
+(setq gnus-group-line-format
+ "%M\%S\%p\%P\%5y: %(%-40,40g%) %d\n")
+@end lisp
+
+This will result in lines looking like:
+
+@example
+* 0: mail.ding 19961002T012943
+ 0: custom 19961002T012713
+@end example
+
+As you can see, the date is displayed in compact ISO 8601 format. This
+may be a bit too much, so to just display the date, you could say
+something like:
+
+@lisp
+(setq gnus-group-line-format
+ "%M\%S\%p\%P\%5y: %(%-40,40g%) %6,6~(cut 2)d\n")
+@end lisp
+
+If you would like greater control of the time format, you can use a
+user-defined format spec. Something like the following should do the
+trick:
+
+@lisp
+(setq gnus-group-line-format
+ "%M\%S\%p\%P\%5y: %(%-40,40g%) %ud\n")
+(defun gnus-user-format-function-d (headers)
+ (let ((time (gnus-group-timestamp gnus-tmp-group)))
+ (if time
+ (format-time-string "%b %d %H:%M" time)
+ "")))
+@end lisp
+
+To see what variables are dynamically bound (like
+@code{gnus-tmp-group}), you have to look at the source code. The
+variable names aren't guaranteed to be stable over Gnus versions,
+either.
+
+
+@node File Commands
+@subsection File Commands
+@cindex file commands
+
+@table @kbd
+
+@item r
+@kindex r (Group)
+@findex gnus-group-read-init-file
+@vindex gnus-init-file
+@cindex reading init file
+Re-read the init file (@code{gnus-init-file}, which defaults to
+@file{~/.gnus.el}) (@code{gnus-group-read-init-file}).
+
+@item s
+@kindex s (Group)
+@findex gnus-group-save-newsrc
+@cindex saving .newsrc
+Save the @file{.newsrc.eld} file (and @file{.newsrc} if wanted)
+(@code{gnus-group-save-newsrc}). If given a prefix, force saving the
+file(s) whether Gnus thinks it is necessary or not.
+
+@c @item Z
+@c @kindex Z (Group)
+@c @findex gnus-group-clear-dribble
+@c Clear the dribble buffer (@code{gnus-group-clear-dribble}).
+
+@end table
+
+
+@node Sieve Commands
+@subsection Sieve Commands
+@cindex group sieve commands
+
+Sieve is a server-side mail filtering language. In Gnus you can use
+the @code{sieve} group parameter (@pxref{Group Parameters}) to specify
+sieve rules that should apply to each group. Gnus provides two
+commands to translate all these group parameters into a proper Sieve
+script that can be transferred to the server somehow.
+
+@vindex gnus-sieve-file
+@vindex gnus-sieve-region-start
+@vindex gnus-sieve-region-end
+The generated Sieve script is placed in @code{gnus-sieve-file} (by
+default @file{~/.sieve}). The Sieve code that Gnus generate is placed
+between two delimiters, @code{gnus-sieve-region-start} and
+@code{gnus-sieve-region-end}, so you may write additional Sieve code
+outside these delimiters that will not be removed the next time you
+regenerate the Sieve script.
+
+@vindex gnus-sieve-crosspost
+The variable @code{gnus-sieve-crosspost} controls how the Sieve script
+is generated. If it is non-@code{nil} (the default) articles is
+placed in all groups that have matching rules, otherwise the article
+is only placed in the group with the first matching rule. For
+example, the group parameter @samp{(sieve address "sender"
+"owner-ding@@hpc.uh.edu")} will generate the following piece of Sieve
+code if @code{gnus-sieve-crosspost} is @code{nil}. (When
+@code{gnus-sieve-crosspost} is non-@code{nil}, it looks the same
+except that the line containing the call to @code{stop} is removed.)
+
+@example
+if address "sender" "owner-ding@@hpc.uh.edu" @{
+ fileinto "INBOX.ding";
+ stop;
+@}
+@end example
+
+@xref{Top, Emacs Sieve, Top, sieve, Emacs Sieve}.
+
+@table @kbd
+
+@item D g
+@kindex D g (Group)
+@findex gnus-sieve-generate
+@vindex gnus-sieve-file
+@cindex generating sieve script
+Regenerate a Sieve script from the @code{sieve} group parameters and
+put you into the @code{gnus-sieve-file} without saving it.
+
+@item D u
+@kindex D u (Group)
+@findex gnus-sieve-update
+@vindex gnus-sieve-file
+@cindex updating sieve script
+Regenerates the Gnus managed part of @code{gnus-sieve-file} using the
+@code{sieve} group parameters, save the file and upload it to the
+server using the @code{sieveshell} program.
+
+@end table
+
+
+@node Summary Buffer
+@chapter Summary Buffer
+@cindex summary buffer
+
+A line for each article is displayed in the summary buffer. You can
+move around, read articles, post articles and reply to articles.
+
+The most common way to a summary buffer is to select a group from the
+group buffer (@pxref{Selecting a Group}).
+
+You can have as many summary buffers open as you wish.
+
+You can customize the Summary Mode tool bar, see @kbd{M-x
+customize-apropos RET gnus-summary-tool-bar}. This feature is only
+available in Emacs.
+
+@kindex v (Summary)
+@cindex keys, reserved for users (Summary)
+The key @kbd{v} is reserved for users. You can bind it to some
+command or better use it as a prefix key. For example:
+@lisp
+(define-key gnus-summary-mode-map (kbd "v -") "LrS") ;; lower subthread
+@end lisp
+
+@menu
+* Summary Buffer Format:: Deciding how the summary buffer is to look.
+* Summary Maneuvering:: Moving around the summary buffer.
+* Choosing Articles:: Reading articles.
+* Paging the Article:: Scrolling the current article.
+* Reply Followup and Post:: Posting articles.
+* Delayed Articles:: Send articles at a later time.
+* Marking Articles:: Marking articles as read, expirable, etc.
+* Limiting:: You can limit the summary buffer.
+* Threading:: How threads are made.
+* Sorting the Summary Buffer:: How articles and threads are sorted.
+* Asynchronous Fetching:: Gnus might be able to pre-fetch articles.
+* Article Caching:: You may store articles in a cache.
+* Persistent Articles:: Making articles expiry-resistant.
+* Sticky Articles:: Article buffers that are not reused.
+* Article Backlog:: Having already read articles hang around.
+* Saving Articles:: Ways of customizing article saving.
+* Decoding Articles:: Gnus can treat series of (uu)encoded articles.
+* Article Treatment:: The article buffer can be mangled at will.
+* MIME Commands:: Doing MIMEy things with the articles.
+* Charsets:: Character set issues.
+* Article Commands:: Doing various things with the article buffer.
+* Summary Sorting:: Sorting the summary buffer in various ways.
+* Finding the Parent:: No child support? Get the parent.
+* Alternative Approaches:: Reading using non-default summaries.
+* Tree Display:: A more visual display of threads.
+* Mail Group Commands:: Some commands can only be used in mail groups.
+* Various Summary Stuff:: What didn't fit anywhere else.
+* Exiting the Summary Buffer:: Returning to the Group buffer,
+ or reselecting the current group.
+* Crosspost Handling:: How crossposted articles are dealt with.
+* Duplicate Suppression:: An alternative when crosspost handling fails.
+* Security:: Decrypt and Verify.
+* Mailing List:: Mailing list minor mode.
+@end menu
+
+
+@node Summary Buffer Format
+@section Summary Buffer Format
+@cindex summary buffer format
+
+@iftex
+@iflatex
+\gnusfigure{The Summary Buffer}{180}{
+\put(0,0){\epsfig{figure=ps/summary,width=7.5cm}}
+\put(445,0){\makebox(0,0)[br]{\epsfig{figure=ps/summary-article,width=7.5cm}}}
+}
+@end iflatex
+@end iftex
+
+@menu
+* Summary Buffer Lines:: You can specify how summary lines should look.
+* To From Newsgroups:: How to not display your own name.
+* Summary Buffer Mode Line:: You can say how the mode line should look.
+* Summary Highlighting:: Making the summary buffer all pretty and nice.
+@end menu
+
+@findex mail-extract-address-components
+@findex gnus-extract-address-components
+@vindex gnus-extract-address-components
+Gnus will use the value of the @code{gnus-extract-address-components}
+variable as a function for getting the name and address parts of a
+@code{From} header. Two pre-defined functions exist:
+@code{gnus-extract-address-components}, which is the default, quite
+fast, and too simplistic solution; and
+@code{mail-extract-address-components}, which works very nicely, but is
+slower. The default function will return the wrong answer in 5% of the
+cases. If this is unacceptable to you, use the other function instead:
+
+@lisp
+(setq gnus-extract-address-components
+ 'mail-extract-address-components)
+@end lisp
+
+@vindex gnus-summary-same-subject
+@code{gnus-summary-same-subject} is a string indicating that the current
+article has the same subject as the previous. This string will be used
+with those specs that require it. The default is @code{""}.
+
+
+@node Summary Buffer Lines
+@subsection Summary Buffer Lines
+
+@vindex gnus-summary-line-format
+You can change the format of the lines in the summary buffer by changing
+the @code{gnus-summary-line-format} variable. It works along the same
+lines as a normal @code{format} string, with some extensions
+(@pxref{Formatting Variables}).
+
+There should always be a colon or a point position marker on the line;
+the cursor always moves to the point position marker or the colon after
+performing an operation. (Of course, Gnus wouldn't be Gnus if it wasn't
+possible to change this. Just write a new function
+@code{gnus-goto-colon} which does whatever you like with the cursor.)
+@xref{Positioning Point}.
+
+The default string is @samp{%U%R%z%I%(%[%4L: %-23,23f%]%) %s\n}.
+
+The following format specification characters and extended format
+specification(s) are understood:
+
+@table @samp
+@item N
+Article number.
+@item S
+Subject string. List identifiers stripped,
+@code{gnus-list-identifiers}. @xref{Article Hiding}.
+@item s
+Subject if the article is the root of the thread or the previous article
+had a different subject, @code{gnus-summary-same-subject} otherwise.
+(@code{gnus-summary-same-subject} defaults to @code{""}.)
+@item F
+Full @code{From} header.
+@item n
+The name (from the @code{From} header).
+@item f
+The name, @code{To} header or the @code{Newsgroups} header (@pxref{To
+From Newsgroups}).
+@item a
+The name (from the @code{From} header). This differs from the @code{n}
+spec in that it uses the function designated by the
+@code{gnus-extract-address-components} variable, which is slower, but
+may be more thorough.
+@item A
+The address (from the @code{From} header). This works the same way as
+the @code{a} spec.
+@item L
+Number of lines in the article.
+@item c
+Number of characters in the article. This specifier is not supported
+in some methods (like nnfolder).
+@item k
+Pretty-printed version of the number of characters in the article;
+for example, @samp{1.2k} or @samp{0.4M}.
+@item I
+Indentation based on thread level (@pxref{Customizing Threading}).
+@item B
+A complex trn-style thread tree, showing response-connecting trace
+lines. A thread could be drawn like this:
+
+@example
+>
++->
+| +->
+| | \->
+| | \->
+| \->
++->
+\->
+@end example
+
+You can customize the appearance with the following options. Note
+that it is possible to make the thread display look really neat by
+replacing the default @acronym{ASCII} characters with graphic
+line-drawing glyphs.
+@table @code
+@item gnus-sum-thread-tree-root
+@vindex gnus-sum-thread-tree-root
+Used for the root of a thread. If @code{nil}, use subject
+instead. The default is @samp{> }.
+
+@item gnus-sum-thread-tree-false-root
+@vindex gnus-sum-thread-tree-false-root
+Used for the false root of a thread (@pxref{Loose Threads}). If
+@code{nil}, use subject instead. The default is @samp{> }.
+
+@item gnus-sum-thread-tree-single-indent
+@vindex gnus-sum-thread-tree-single-indent
+Used for a thread with just one message. If @code{nil}, use subject
+instead. The default is @samp{}.
+
+@item gnus-sum-thread-tree-vertical
+@vindex gnus-sum-thread-tree-vertical
+Used for drawing a vertical line. The default is @samp{| }.
+
+@item gnus-sum-thread-tree-indent
+@vindex gnus-sum-thread-tree-indent
+Used for indenting. The default is @samp{ }.
+
+@item gnus-sum-thread-tree-leaf-with-other
+@vindex gnus-sum-thread-tree-leaf-with-other
+Used for a leaf with brothers. The default is @samp{+-> }.
+
+@item gnus-sum-thread-tree-single-leaf
+@vindex gnus-sum-thread-tree-single-leaf
+Used for a leaf without brothers. The default is @samp{\-> }
+
+@end table
+
+@item T
+Nothing if the article is a root and lots of spaces if it isn't (it
+pushes everything after it off the screen).
+@item [
+Opening bracket, which is normally @samp{[}, but can also be @samp{<}
+for adopted articles (@pxref{Customizing Threading}).
+@item ]
+Closing bracket, which is normally @samp{]}, but can also be @samp{>}
+for adopted articles.
+@item >
+One space for each thread level.
+@item <
+Twenty minus thread level spaces.
+@item U
+Unread. @xref{Read Articles}.
+
+@item R
+This misleadingly named specifier is the @dfn{secondary mark}. This
+mark will say whether the article has been replied to, has been cached,
+or has been saved. @xref{Other Marks}.
+
+@item i
+Score as a number (@pxref{Scoring}).
+@item z
+@vindex gnus-summary-zcore-fuzz
+Zcore, @samp{+} if above the default level and @samp{-} if below the
+default level. If the difference between
+@code{gnus-summary-default-score} and the score is less than
+@code{gnus-summary-zcore-fuzz}, this spec will not be used.
+@item V
+Total thread score.
+@item x
+@code{Xref}.
+@item D
+@code{Date}.
+@item d
+The @code{Date} in @code{DD-MMM} format.
+@item o
+The @code{Date} in @var{YYYYMMDD}@code{T}@var{HHMMSS} format.
+@item M
+@code{Message-ID}.
+@item r
+@code{References}.
+@item t
+Number of articles in the current sub-thread. Using this spec will slow
+down summary buffer generation somewhat.
+@item e
+An @samp{=} (@code{gnus-not-empty-thread-mark}) will be displayed if the
+article has any children.
+@item P
+The line number.
+@item O
+Download mark.
+@item *
+Desired cursor position (instead of after first colon).
+@item &user-date;
+Age sensitive date format. Various date format is defined in
+@code{gnus-user-date-format-alist}.
+@item u
+User defined specifier. The next character in the format string should
+be a letter. Gnus will call the function
+@code{gnus-user-format-function-@var{x}}, where @var{x} is the letter
+following @samp{%u}. The function will be passed the current header as
+argument. The function should return a string, which will be inserted
+into the summary just like information from any other summary specifier.
+@end table
+
+Text between @samp{%(} and @samp{%)} will be highlighted with
+@code{gnus-mouse-face} when the mouse point is placed inside the area.
+There can only be one such area.
+
+The @samp{%U} (status), @samp{%R} (replied) and @samp{%z} (zcore) specs
+have to be handled with care. For reasons of efficiency, Gnus will
+compute what column these characters will end up in, and ``hard-code''
+that. This means that it is invalid to have these specs after a
+variable-length spec. Well, you might not be arrested, but your summary
+buffer will look strange, which is bad enough.
+
+The smart choice is to have these specs as far to the left as possible.
+(Isn't that the case with everything, though? But I digress.)
+
+This restriction may disappear in later versions of Gnus.
+
+
+@node To From Newsgroups
+@subsection To From Newsgroups
+@cindex To
+@cindex Newsgroups
+
+In some groups (particularly in archive groups), the @code{From} header
+isn't very interesting, since all the articles there are written by
+you. To display the information in the @code{To} or @code{Newsgroups}
+headers instead, you need to decide three things: What information to
+gather; where to display it; and when to display it.
+
+@enumerate
+@item
+@vindex gnus-extra-headers
+The reading of extra header information is controlled by the
+@code{gnus-extra-headers}. This is a list of header symbols. For
+instance:
+
+@lisp
+(setq gnus-extra-headers
+ '(To Newsgroups X-Newsreader))
+@end lisp
+
+This will result in Gnus trying to obtain these three headers, and
+storing it in header structures for later easy retrieval.
+
+@item
+@findex gnus-extra-header
+The value of these extra headers can be accessed via the
+@code{gnus-extra-header} function. Here's a format line spec that will
+access the @code{X-Newsreader} header:
+
+@example
+"%~(form (gnus-extra-header 'X-Newsreader))@@"
+@end example
+
+@item
+@vindex gnus-ignored-from-addresses
+The @code{gnus-ignored-from-addresses} variable says when the @samp{%f}
+summary line spec returns the @code{To}, @code{Newsreader} or
+@code{From} header. If this regexp matches the contents of the
+@code{From} header, the value of the @code{To} or @code{Newsreader}
+headers are used instead.
+
+To distinguish regular articles from those where the @code{From} field
+has been swapped, a string is prefixed to the @code{To} or
+@code{Newsgroups} header in the summary line. By default the string is
+@samp{-> } for @code{To} and @samp{=> } for @code{Newsgroups}, you can
+customize these strings with @code{gnus-summary-to-prefix} and
+@code{gnus-summary-newsgroup-prefix}.
+
+@end enumerate
+
+@vindex nnmail-extra-headers
+A related variable is @code{nnmail-extra-headers}, which controls when
+to include extra headers when generating overview (@acronym{NOV}) files.
+If you have old overview files, you should regenerate them after
+changing this variable, by entering the server buffer using @kbd{^},
+and then @kbd{g} on the appropriate mail server (e.g., nnml) to cause
+regeneration.
+
+@vindex gnus-summary-line-format
+You also have to instruct Gnus to display the data by changing the
+@code{%n} spec to the @code{%f} spec in the
+@code{gnus-summary-line-format} variable.
+
+In summary, you'd typically put something like the following in
+@file{~/.gnus.el}:
+
+@lisp
+(setq gnus-extra-headers
+ '(To Newsgroups))
+(setq nnmail-extra-headers gnus-extra-headers)
+(setq gnus-summary-line-format
+ "%U%R%z%I%(%[%4L: %-23,23f%]%) %s\n")
+(setq gnus-ignored-from-addresses
+ "Your Name Here")
+@end lisp
+
+(The values listed above are the default values in Gnus. Alter them
+to fit your needs.)
+
+A note for news server administrators, or for users who wish to try to
+convince their news server administrator to provide some additional
+support:
+
+The above is mostly useful for mail groups, where you have control over
+the @acronym{NOV} files that are created. However, if you can persuade your
+nntp admin to add (in the usual implementation, notably INN):
+
+@example
+Newsgroups:full
+@end example
+
+to the end of her @file{overview.fmt} file, then you can use that just
+as you would the extra headers from the mail groups.
+
+
+@node Summary Buffer Mode Line
+@subsection Summary Buffer Mode Line
+
+@vindex gnus-summary-mode-line-format
+You can also change the format of the summary mode bar (@pxref{Mode Line
+Formatting}). Set @code{gnus-summary-mode-line-format} to whatever you
+like. The default is @samp{Gnus: %%b [%A] %Z}.
+
+Here are the elements you can play with:
+
+@table @samp
+@item G
+Group name.
+@item p
+Unprefixed group name.
+@item A
+Current article number.
+@item z
+Current article score.
+@item V
+Gnus version.
+@item U
+Number of unread articles in this group.
+@item e
+Number of unread articles in this group that aren't displayed in the
+summary buffer.
+@item Z
+A string with the number of unread and unselected articles represented
+either as @samp{<%U(+%e) more>} if there are both unread and unselected
+articles, and just as @samp{<%U more>} if there are just unread articles
+and no unselected ones.
+@item g
+Shortish group name. For instance, @samp{rec.arts.anime} will be
+shortened to @samp{r.a.anime}.
+@item S
+Subject of the current article.
+@item u
+User-defined spec (@pxref{User-Defined Specs}).
+@item s
+Name of the current score file (@pxref{Scoring}).
+@item d
+Number of dormant articles (@pxref{Unread Articles}).
+@item t
+Number of ticked articles (@pxref{Unread Articles}).
+@item r
+Number of articles that have been marked as read in this session.
+@item E
+Number of articles expunged by the score files.
+@end table
+
+
+@node Summary Highlighting
+@subsection Summary Highlighting
+
+@table @code
+
+@item gnus-visual-mark-article-hook
+@vindex gnus-visual-mark-article-hook
+This hook is run after selecting an article. It is meant to be used for
+highlighting the article in some way. It is not run if
+@code{gnus-visual} is @code{nil}.
+
+@item gnus-summary-update-hook
+@vindex gnus-summary-update-hook
+This hook is called when a summary line is changed. It is not run if
+@code{gnus-visual} is @code{nil}.
+
+@item gnus-summary-selected-face
+@vindex gnus-summary-selected-face
+This is the face (or @dfn{font} as some people call it) used to
+highlight the current article in the summary buffer.
+
+@item gnus-summary-highlight
+@vindex gnus-summary-highlight
+Summary lines are highlighted according to this variable, which is a
+list where the elements are of the format @code{(@var{form}
+. @var{face})}. If you would, for instance, like ticked articles to be
+italic and high-scored articles to be bold, you could set this variable
+to something like
+@lisp
+(((eq mark gnus-ticked-mark) . italic)
+ ((> score default) . bold))
+@end lisp
+As you may have guessed, if @var{form} returns a non-@code{nil} value,
+@var{face} will be applied to the line.
+@end table
+
+
+@node Summary Maneuvering
+@section Summary Maneuvering
+@cindex summary movement
+
+All the straight movement commands understand the numeric prefix and
+behave pretty much as you'd expect.
+
+None of these commands select articles.
+
+@table @kbd
+@item G M-n
+@itemx M-n
+@kindex M-n (Summary)
+@kindex G M-n (Summary)
+@findex gnus-summary-next-unread-subject
+Go to the next summary line of an unread article
+(@code{gnus-summary-next-unread-subject}).
+
+@item G M-p
+@itemx M-p
+@kindex M-p (Summary)
+@kindex G M-p (Summary)
+@findex gnus-summary-prev-unread-subject
+Go to the previous summary line of an unread article
+(@code{gnus-summary-prev-unread-subject}).
+
+@item G g
+@kindex G g (Summary)
+@findex gnus-summary-goto-subject
+Ask for an article number and then go to the summary line of that article
+without displaying the article (@code{gnus-summary-goto-subject}).
+@end table
+
+If Gnus asks you to press a key to confirm going to the next group, you
+can use the @kbd{C-n} and @kbd{C-p} keys to move around the group
+buffer, searching for the next group to read without actually returning
+to the group buffer.
+
+Variables related to summary movement:
+
+@table @code
+
+@vindex gnus-auto-select-next
+@item gnus-auto-select-next
+If you issue one of the movement commands (like @kbd{n}) and there are
+no more unread articles after the current one, Gnus will offer to go to
+the next group. If this variable is @code{t} and the next group is
+empty, Gnus will exit summary mode and return to the group buffer. If
+this variable is neither @code{t} nor @code{nil}, Gnus will select the
+next group with unread articles. As a special case, if this variable
+is @code{quietly}, Gnus will select the next group without asking for
+confirmation. If this variable is @code{almost-quietly}, the same
+will happen only if you are located on the last article in the group.
+Finally, if this variable is @code{slightly-quietly}, the @kbd{Z n}
+command will go to the next group without confirmation. Also
+@pxref{Group Levels}.
+
+@item gnus-auto-select-same
+@vindex gnus-auto-select-same
+If non-@code{nil}, all the movement commands will try to go to the next
+article with the same subject as the current. (@dfn{Same} here might
+mean @dfn{roughly equal}. See @code{gnus-summary-gather-subject-limit}
+for details (@pxref{Customizing Threading}).) If there are no more
+articles with the same subject, go to the first unread article.
+
+This variable is not particularly useful if you use a threaded display.
+
+@item gnus-summary-check-current
+@vindex gnus-summary-check-current
+If non-@code{nil}, all the ``unread'' movement commands will not proceed
+to the next (or previous) article if the current article is unread.
+Instead, they will choose the current article.
+
+@item gnus-auto-center-summary
+@vindex gnus-auto-center-summary
+If non-@code{nil}, Gnus will keep the point in the summary buffer
+centered at all times. This makes things quite tidy, but if you have a
+slow network connection, or simply do not like this un-Emacsism, you can
+set this variable to @code{nil} to get the normal Emacs scrolling
+action. This will also inhibit horizontal re-centering of the summary
+buffer, which might make it more inconvenient to read extremely long
+threads.
+
+This variable can also be a number. In that case, center the window at
+the given number of lines from the top.
+
+@item gnus-summary-stop-at-end-of-message
+@vindex gnus-summary-stop-at-end-of-message
+If non-@code{nil}, don't go to the next article when hitting
+@kbd{SPC}, and you're at the end of the article.
+
+@end table
+
+
+@node Choosing Articles
+@section Choosing Articles
+@cindex selecting articles
+
+@menu
+* Choosing Commands:: Commands for choosing articles.
+* Choosing Variables:: Variables that influence these commands.
+@end menu
+
+
+@node Choosing Commands
+@subsection Choosing Commands
+
+None of the following movement commands understand the numeric prefix,
+and they all select and display an article.
+
+If you want to fetch new articles or redisplay the group, see
+@ref{Exiting the Summary Buffer}.
+
+@table @kbd
+@item SPACE
+@kindex SPACE (Summary)
+@findex gnus-summary-next-page
+Select the current article, or, if that one's read already, the next
+unread article (@code{gnus-summary-next-page}).
+
+If you have an article window open already and you press @kbd{SPACE}
+again, the article will be scrolled. This lets you conveniently
+@kbd{SPACE} through an entire newsgroup. @xref{Paging the Article}.
+
+@item G n
+@itemx n
+@kindex n (Summary)
+@kindex G n (Summary)
+@findex gnus-summary-next-unread-article
+@c @icon{gnus-summary-next-unread}
+Go to next unread article (@code{gnus-summary-next-unread-article}).
+
+@item G p
+@itemx p
+@kindex p (Summary)
+@findex gnus-summary-prev-unread-article
+@c @icon{gnus-summary-prev-unread}
+Go to previous unread article (@code{gnus-summary-prev-unread-article}).
+
+@item G N
+@itemx N
+@kindex N (Summary)
+@kindex G N (Summary)
+@findex gnus-summary-next-article
+Go to the next article (@code{gnus-summary-next-article}).
+
+@item G P
+@itemx P
+@kindex P (Summary)
+@kindex G P (Summary)
+@findex gnus-summary-prev-article
+Go to the previous article (@code{gnus-summary-prev-article}).
+
+@item G C-n
+@kindex G C-n (Summary)
+@findex gnus-summary-next-same-subject
+Go to the next article with the same subject
+(@code{gnus-summary-next-same-subject}).
+
+@item G C-p
+@kindex G C-p (Summary)
+@findex gnus-summary-prev-same-subject
+Go to the previous article with the same subject
+(@code{gnus-summary-prev-same-subject}).
+
+@item G f
+@itemx .
+@kindex G f (Summary)
+@kindex . (Summary)
+@findex gnus-summary-first-unread-article
+Go to the first unread article
+(@code{gnus-summary-first-unread-article}).
+
+@item G b
+@itemx ,
+@kindex G b (Summary)
+@kindex , (Summary)
+@findex gnus-summary-best-unread-article
+Go to the unread article with the highest score
+(@code{gnus-summary-best-unread-article}). If given a prefix argument,
+go to the first unread article that has a score over the default score.
+
+@item G l
+@itemx l
+@kindex l (Summary)
+@kindex G l (Summary)
+@findex gnus-summary-goto-last-article
+Go to the previous article read (@code{gnus-summary-goto-last-article}).
+
+@item G o
+@kindex G o (Summary)
+@findex gnus-summary-pop-article
+@cindex history
+@cindex article history
+Pop an article off the summary history and go to this article
+(@code{gnus-summary-pop-article}). This command differs from the
+command above in that you can pop as many previous articles off the
+history as you like, while @kbd{l} toggles the two last read articles.
+For a somewhat related issue (if you use these commands a lot),
+@pxref{Article Backlog}.
+
+@item G j
+@itemx j
+@kindex j (Summary)
+@kindex G j (Summary)
+@findex gnus-summary-goto-article
+Ask for an article number or @code{Message-ID}, and then go to that
+article (@code{gnus-summary-goto-article}).
+
+@end table
+
+
+@node Choosing Variables
+@subsection Choosing Variables
+
+Some variables relevant for moving and selecting articles:
+
+@table @code
+@item gnus-auto-extend-newsgroup
+@vindex gnus-auto-extend-newsgroup
+All the movement commands will try to go to the previous (or next)
+article, even if that article isn't displayed in the Summary buffer if
+this variable is non-@code{nil}. Gnus will then fetch the article from
+the server and display it in the article buffer.
+
+@item gnus-select-article-hook
+@vindex gnus-select-article-hook
+This hook is called whenever an article is selected. The default is
+@code{nil}. If you would like each article to be saved in the Agent as
+you read it, putting @code{gnus-agent-fetch-selected-article} on this
+hook will do so.
+
+@item gnus-mark-article-hook
+@vindex gnus-mark-article-hook
+@findex gnus-summary-mark-unread-as-read
+@findex gnus-summary-mark-read-and-unread-as-read
+@findex gnus-unread-mark
+This hook is called whenever an article is selected. It is intended to
+be used for marking articles as read. The default value is
+@code{gnus-summary-mark-read-and-unread-as-read}, and will change the
+mark of almost any article you read to @code{gnus-read-mark}. The only
+articles not affected by this function are ticked, dormant, and
+expirable articles. If you'd instead like to just have unread articles
+marked as read, you can use @code{gnus-summary-mark-unread-as-read}
+instead. It will leave marks like @code{gnus-low-score-mark},
+@code{gnus-del-mark} (and so on) alone.
+
+@end table
+
+
+@node Paging the Article
+@section Scrolling the Article
+@cindex article scrolling
+
+@table @kbd
+
+@item SPACE
+@kindex SPACE (Summary)
+@findex gnus-summary-next-page
+Pressing @kbd{SPACE} will scroll the current article forward one page,
+or, if you have come to the end of the current article, will choose the
+next article (@code{gnus-summary-next-page}).
+
+@vindex gnus-article-boring-faces
+@vindex gnus-article-skip-boring
+If @code{gnus-article-skip-boring} is non-@code{nil} and the rest of
+the article consists only of citations and signature, then it will be
+skipped; the next article will be shown instead. You can customize
+what is considered uninteresting with
+@code{gnus-article-boring-faces}. You can manually view the article's
+pages, no matter how boring, using @kbd{C-M-v}.
+
+@item DEL
+@kindex DEL (Summary)
+@findex gnus-summary-prev-page
+Scroll the current article back one page (@code{gnus-summary-prev-page}).
+
+@item RET
+@kindex RET (Summary)
+@findex gnus-summary-scroll-up
+Scroll the current article one line forward
+(@code{gnus-summary-scroll-up}).
+
+@item M-RET
+@kindex M-RET (Summary)
+@findex gnus-summary-scroll-down
+Scroll the current article one line backward
+(@code{gnus-summary-scroll-down}).
+
+@item A g
+@itemx g
+@kindex A g (Summary)
+@kindex g (Summary)
+@findex gnus-summary-show-article
+@vindex gnus-summary-show-article-charset-alist
+(Re)fetch the current article (@code{gnus-summary-show-article}). If
+given a prefix, show a completely ``raw'' article, just the way it
+came from the server. If given a prefix twice (i.e., @kbd{C-u C-u
+g'}), fetch the current article, but don't run any of the article
+treatment functions.
+
+@cindex charset, view article with different charset
+If given a numerical prefix, you can do semi-manual charset stuff.
+@kbd{C-u 0 g cn-gb-2312 RET} will decode the message as if it were
+encoded in the @code{cn-gb-2312} charset. If you have
+
+@lisp
+(setq gnus-summary-show-article-charset-alist
+ '((1 . cn-gb-2312)
+ (2 . big5)))
+@end lisp
+
+then you can say @kbd{C-u 1 g} to get the same effect.
+
+@item A <
+@itemx <
+@kindex < (Summary)
+@kindex A < (Summary)
+@findex gnus-summary-beginning-of-article
+Scroll to the beginning of the article
+(@code{gnus-summary-beginning-of-article}).
+
+@item A >
+@itemx >
+@kindex > (Summary)
+@kindex A > (Summary)
+@findex gnus-summary-end-of-article
+Scroll to the end of the article (@code{gnus-summary-end-of-article}).
+
+@item A s
+@itemx s
+@kindex A s (Summary)
+@kindex s (Summary)
+@findex gnus-summary-isearch-article
+Perform an isearch in the article buffer
+(@code{gnus-summary-isearch-article}).
+
+@item h
+@kindex h (Summary)
+@findex gnus-summary-select-article-buffer
+Select the article buffer (@code{gnus-summary-select-article-buffer}).
+
+@end table
+
+
+@node Reply Followup and Post
+@section Reply, Followup and Post
+
+@menu
+* Summary Mail Commands:: Sending mail.
+* Summary Post Commands:: Sending news.
+* Summary Message Commands:: Other Message-related commands.
+* Canceling and Superseding::
+@end menu
+
+
+@node Summary Mail Commands
+@subsection Summary Mail Commands
+@cindex mail
+@cindex composing mail
+
+Commands for composing a mail message:
+
+@table @kbd
+
+@item S r
+@itemx r
+@kindex S r (Summary)
+@kindex r (Summary)
+@findex gnus-summary-reply
+@c @icon{gnus-summary-mail-reply}
+@c @icon{gnus-summary-reply}
+Mail a reply to the author of the current article
+(@code{gnus-summary-reply}).
+
+@item S R
+@itemx R
+@kindex R (Summary)
+@kindex S R (Summary)
+@findex gnus-summary-reply-with-original
+@c @icon{gnus-summary-reply-with-original}
+Mail a reply to the author of the current article and include the
+original message (@code{gnus-summary-reply-with-original}). This
+command uses the process/prefix convention.
+
+@item S w
+@kindex S w (Summary)
+@findex gnus-summary-wide-reply
+Mail a wide reply to the author of the current article
+(@code{gnus-summary-wide-reply}). A @dfn{wide reply} is a reply that
+goes out to all people listed in the @code{To}, @code{From} (or
+@code{Reply-to}) and @code{Cc} headers. If @code{Mail-Followup-To} is
+present, that's used instead.
+
+@item S W
+@kindex S W (Summary)
+@findex gnus-summary-wide-reply-with-original
+Mail a wide reply to the current article and include the original
+message (@code{gnus-summary-wide-reply-with-original}). This command uses
+the process/prefix convention, but only uses the headers from the
+first article to determine the recipients.
+
+@item S L
+@kindex S L (Summary)
+@findex gnus-summary-reply-to-list-with-original
+When replying to a message from a mailing list, send a reply to that
+message to the mailing list, and include the original message
+(@code{gnus-summary-reply-to-list-with-original}).
+
+@item S v
+@kindex S v (Summary)
+@findex gnus-summary-very-wide-reply
+Mail a very wide reply to the author of the current article
+(@code{gnus-summary-wide-reply}). A @dfn{very wide reply} is a reply
+that goes out to all people listed in the @code{To}, @code{From} (or
+@code{Reply-to}) and @code{Cc} headers in all the process/prefixed
+articles. This command uses the process/prefix convention.
+
+@item S V
+@kindex S V (Summary)
+@findex gnus-summary-very-wide-reply-with-original
+Mail a very wide reply to the author of the current article and include the
+original message (@code{gnus-summary-very-wide-reply-with-original}). This
+command uses the process/prefix convention.
+
+@item S B r
+@kindex S B r (Summary)
+@findex gnus-summary-reply-broken-reply-to
+Mail a reply to the author of the current article but ignore the
+@code{Reply-To} field (@code{gnus-summary-reply-broken-reply-to}).
+If you need this because a mailing list incorrectly sets a
+@code{Reply-To} header pointing to the list, you probably want to set
+the @code{broken-reply-to} group parameter instead, so things will work
+correctly. @xref{Group Parameters}.
+
+@item S B R
+@kindex S B R (Summary)
+@findex gnus-summary-reply-broken-reply-to-with-original
+Mail a reply to the author of the current article and include the
+original message but ignore the @code{Reply-To} field
+(@code{gnus-summary-reply-broken-reply-to-with-original}).
+
+@item S o m
+@itemx C-c C-f
+@kindex S o m (Summary)
+@kindex C-c C-f (Summary)
+@findex gnus-summary-mail-forward
+@c @icon{gnus-summary-mail-forward}
+Forward the current article to some other person
+(@code{gnus-summary-mail-forward}). If no prefix is given, the message
+is forwarded according to the value of (@code{message-forward-as-mime})
+and (@code{message-forward-show-mml}); if the prefix is 1, decode the
+message and forward directly inline; if the prefix is 2, forward message
+as an rfc822 @acronym{MIME} section; if the prefix is 3, decode message and
+forward as an rfc822 @acronym{MIME} section; if the prefix is 4, forward message
+directly inline; otherwise, the message is forwarded as no prefix given
+but use the flipped value of (@code{message-forward-as-mime}). By
+default, the message is decoded and forwarded as an rfc822 @acronym{MIME}
+section.
+
+@item S m
+@itemx m
+@kindex m (Summary)
+@kindex S m (Summary)
+@findex gnus-summary-mail-other-window
+@c @icon{gnus-summary-mail-originate}
+Prepare a mail (@code{gnus-summary-mail-other-window}). By default, use
+the posting style of the current group. If given a prefix, disable that.
+If the prefix is 1, prompt for a group name to find the posting style.
+
+@item S i
+@kindex S i (Summary)
+@findex gnus-summary-news-other-window
+Prepare a news (@code{gnus-summary-news-other-window}). By default,
+post to the current group. If given a prefix, disable that. If the
+prefix is 1, prompt for a group to post to.
+
+This function actually prepares a news even when using mail groups.
+This is useful for ``posting'' messages to mail groups without actually
+sending them over the network: they're just saved directly to the group
+in question. The corresponding back end must have a request-post method
+for this to work though.
+
+@item S D b
+@kindex S D b (Summary)
+@findex gnus-summary-resend-bounced-mail
+@cindex bouncing mail
+If you have sent a mail, but the mail was bounced back to you for some
+reason (wrong address, transient failure), you can use this command to
+resend that bounced mail (@code{gnus-summary-resend-bounced-mail}). You
+will be popped into a mail buffer where you can edit the headers before
+sending the mail off again. If you give a prefix to this command, and
+the bounced mail is a reply to some other mail, Gnus will try to fetch
+that mail and display it for easy perusal of its headers. This might
+very well fail, though.
+
+@item S D r
+@kindex S D r (Summary)
+@findex gnus-summary-resend-message
+Not to be confused with the previous command,
+@code{gnus-summary-resend-message} will prompt you for an address to
+send the current message off to, and then send it to that place. The
+headers of the message won't be altered---but lots of headers that say
+@code{Resent-To}, @code{Resent-From} and so on will be added. This
+means that you actually send a mail to someone that has a @code{To}
+header that (probably) points to yourself. This will confuse people.
+So, natcherly you'll only do that if you're really eVIl.
+
+This command is mainly used if you have several accounts and want to
+ship a mail to a different account of yours. (If you're both
+@code{root} and @code{postmaster} and get a mail for @code{postmaster}
+to the @code{root} account, you may want to resend it to
+@code{postmaster}. Ordnung muss sein!
+
+This command understands the process/prefix convention
+(@pxref{Process/Prefix}).
+
+@item S D e
+@kindex S D e (Summary)
+@findex gnus-summary-resend-message-edit
+
+Like the previous command, but will allow you to edit the message as
+if it were a new message before resending.
+
+@item S O m
+@kindex S O m (Summary)
+@findex gnus-uu-digest-mail-forward
+Digest the current series (@pxref{Decoding Articles}) and forward the
+result using mail (@code{gnus-uu-digest-mail-forward}). This command
+uses the process/prefix convention (@pxref{Process/Prefix}).
+
+@item S M-c
+@kindex S M-c (Summary)
+@findex gnus-summary-mail-crosspost-complaint
+@cindex crossposting
+@cindex excessive crossposting
+Send a complaint about excessive crossposting to the author of the
+current article (@code{gnus-summary-mail-crosspost-complaint}).
+
+@findex gnus-crosspost-complaint
+This command is provided as a way to fight back against the current
+crossposting pandemic that's sweeping Usenet. It will compose a reply
+using the @code{gnus-crosspost-complaint} variable as a preamble. This
+command understands the process/prefix convention
+(@pxref{Process/Prefix}) and will prompt you before sending each mail.
+
+@end table
+
+Also @xref{Header Commands, ,Header Commands, message, The Message
+Manual}, for more information.
+
+
+@node Summary Post Commands
+@subsection Summary Post Commands
+@cindex post
+@cindex composing news
+
+Commands for posting a news article:
+
+@table @kbd
+@item S p
+@itemx a
+@kindex a (Summary)
+@kindex S p (Summary)
+@findex gnus-summary-post-news
+@c @icon{gnus-summary-post-news}
+Prepare for posting an article (@code{gnus-summary-post-news}). By
+default, post to the current group. If given a prefix, disable that.
+If the prefix is 1, prompt for another group instead.
+
+@item S f
+@itemx f
+@kindex f (Summary)
+@kindex S f (Summary)
+@findex gnus-summary-followup
+@c @icon{gnus-summary-followup}
+Post a followup to the current article (@code{gnus-summary-followup}).
+
+@item S F
+@itemx F
+@kindex S F (Summary)
+@kindex F (Summary)
+@c @icon{gnus-summary-followup-with-original}
+@findex gnus-summary-followup-with-original
+Post a followup to the current article and include the original message
+(@code{gnus-summary-followup-with-original}). This command uses the
+process/prefix convention.
+
+@item S n
+@kindex S n (Summary)
+@findex gnus-summary-followup-to-mail
+Post a followup to the current article via news, even if you got the
+message through mail (@code{gnus-summary-followup-to-mail}).
+
+@item S N
+@kindex S N (Summary)
+@findex gnus-summary-followup-to-mail-with-original
+Post a followup to the current article via news, even if you got the
+message through mail and include the original message
+(@code{gnus-summary-followup-to-mail-with-original}). This command uses
+the process/prefix convention.
+
+@item S o p
+@kindex S o p (Summary)
+@findex gnus-summary-post-forward
+Forward the current article to a newsgroup
+(@code{gnus-summary-post-forward}).
+ If no prefix is given, the message is forwarded according to the value
+of (@code{message-forward-as-mime}) and
+(@code{message-forward-show-mml}); if the prefix is 1, decode the
+message and forward directly inline; if the prefix is 2, forward message
+as an rfc822 @acronym{MIME} section; if the prefix is 3, decode message and
+forward as an rfc822 @acronym{MIME} section; if the prefix is 4, forward message
+directly inline; otherwise, the message is forwarded as no prefix given
+but use the flipped value of (@code{message-forward-as-mime}). By
+default, the message is decoded and forwarded as an rfc822 @acronym{MIME} section.
+
+@item S O p
+@kindex S O p (Summary)
+@findex gnus-uu-digest-post-forward
+@cindex digests
+@cindex making digests
+Digest the current series and forward the result to a newsgroup
+(@code{gnus-uu-digest-post-forward}). This command uses the
+process/prefix convention.
+
+@item S u
+@kindex S u (Summary)
+@findex gnus-uu-post-news
+@c @icon{gnus-uu-post-news}
+Uuencode a file, split it into parts, and post it as a series
+(@code{gnus-uu-post-news}). (@pxref{Uuencoding and Posting}).
+@end table
+
+Also @xref{Header Commands, ,Header Commands, message, The Message
+Manual}, for more information.
+
+
+@node Summary Message Commands
+@subsection Summary Message Commands
+
+@table @kbd
+@item S y
+@kindex S y (Summary)
+@findex gnus-summary-yank-message
+Yank the current article into an already existing Message composition
+buffer (@code{gnus-summary-yank-message}). This command prompts for
+what message buffer you want to yank into, and understands the
+process/prefix convention (@pxref{Process/Prefix}).
+
+@end table
+
+
+@node Canceling and Superseding
+@subsection Canceling Articles
+@cindex canceling articles
+@cindex superseding articles
+
+Have you ever written something, and then decided that you really,
+really, really wish you hadn't posted that?
+
+Well, you can't cancel mail, but you can cancel posts.
+
+@findex gnus-summary-cancel-article
+@kindex C (Summary)
+@c @icon{gnus-summary-cancel-article}
+Find the article you wish to cancel (you can only cancel your own
+articles, so don't try any funny stuff). Then press @kbd{C} or @kbd{S
+c} (@code{gnus-summary-cancel-article}). Your article will be
+canceled---machines all over the world will be deleting your article.
+This command uses the process/prefix convention (@pxref{Process/Prefix}).
+
+Be aware, however, that not all sites honor cancels, so your article may
+live on here and there, while most sites will delete the article in
+question.
+
+Gnus will use the ``current'' select method when canceling. If you
+want to use the standard posting method, use the @samp{a} symbolic
+prefix (@pxref{Symbolic Prefixes}).
+
+Gnus ensures that only you can cancel your own messages using a
+@code{Cancel-Lock} header (@pxref{Canceling News, Canceling News, ,
+message, Message Manual}).
+
+If you discover that you have made some mistakes and want to do some
+corrections, you can post a @dfn{superseding} article that will replace
+your original article.
+
+@findex gnus-summary-supersede-article
+@kindex S (Summary)
+Go to the original article and press @kbd{S s}
+(@code{gnus-summary-supersede-article}). You will be put in a buffer
+where you can edit the article all you want before sending it off the
+usual way.
+
+The same goes for superseding as for canceling, only more so: Some
+sites do not honor superseding. On those sites, it will appear that you
+have posted almost the same article twice.
+
+If you have just posted the article, and change your mind right away,
+there is a trick you can use to cancel/supersede the article without
+waiting for the article to appear on your site first. You simply return
+to the post buffer (which is called @file{*sent ...*}). There you will
+find the article you just posted, with all the headers intact. Change
+the @code{Message-ID} header to a @code{Cancel} or @code{Supersedes}
+header by substituting one of those words for the word
+@code{Message-ID}. Then just press @kbd{C-c C-c} to send the article as
+you would do normally. The previous article will be
+canceled/superseded.
+
+Just remember, kids: There is no 'c' in 'supersede'.
+
+@node Delayed Articles
+@section Delayed Articles
+@cindex delayed sending
+@cindex send delayed
+
+Sometimes, you might wish to delay the sending of a message. For
+example, you might wish to arrange for a message to turn up just in time
+to remind your about the birthday of your Significant Other. For this,
+there is the @code{gnus-delay} package. Setup is simple:
+
+@lisp
+(gnus-delay-initialize)
+@end lisp
+
+@findex gnus-delay-article
+Normally, to send a message you use the @kbd{C-c C-c} command from
+Message mode. To delay a message, use @kbd{C-c C-j}
+(@code{gnus-delay-article}) instead. This will ask you for how long the
+message should be delayed. Possible answers are:
+
+@itemize @bullet
+@item
+A time span. Consists of an integer and a letter. For example,
+@code{42d} means to delay for 42 days. Available letters are @code{m}
+(minutes), @code{h} (hours), @code{d} (days), @code{w} (weeks), @code{M}
+(months) and @code{Y} (years).
+
+@item
+A specific date. Looks like @code{YYYY-MM-DD}. The message will be
+delayed until that day, at a specific time (eight o'clock by default).
+See also @code{gnus-delay-default-hour}.
+
+@item
+A specific time of day. Given in @code{hh:mm} format, 24h, no am/pm
+stuff. The deadline will be at that time today, except if that time has
+already passed, then it's at the given time tomorrow. So if it's ten
+o'clock in the morning and you specify @code{11:15}, then the deadline
+is one hour and fifteen minutes hence. But if you specify @code{9:20},
+that means a time tomorrow.
+@end itemize
+
+The action of the @code{gnus-delay-article} command is influenced by a
+couple of variables:
+
+@table @code
+@item gnus-delay-default-hour
+@vindex gnus-delay-default-hour
+When you specify a specific date, the message will be due on that hour
+on the given date. Possible values are integers 0 through 23.
+
+@item gnus-delay-default-delay
+@vindex gnus-delay-default-delay
+This is a string and gives the default delay. It can be of any of the
+formats described above.
+
+@item gnus-delay-group
+@vindex gnus-delay-group
+Delayed articles will be kept in this group on the drafts server until
+they are due. You probably don't need to change this. The default
+value is @code{"delayed"}.
+
+@item gnus-delay-header
+@vindex gnus-delay-header
+The deadline for each article will be stored in a header. This variable
+is a string and gives the header name. You probably don't need to
+change this. The default value is @code{"X-Gnus-Delayed"}.
+@end table
+
+The way delaying works is like this: when you use the
+@code{gnus-delay-article} command, you give a certain delay. Gnus
+calculates the deadline of the message and stores it in the
+@code{X-Gnus-Delayed} header and puts the message in the
+@code{nndraft:delayed} group.
+
+@findex gnus-delay-send-queue
+And whenever you get new news, Gnus looks through the group for articles
+which are due and sends them. It uses the @code{gnus-delay-send-queue}
+function for this. By default, this function is added to the hook
+@code{gnus-get-new-news-hook}. But of course, you can change this.
+Maybe you want to use the demon to send drafts? Just tell the demon to
+execute the @code{gnus-delay-send-queue} function.
+
+@table @code
+@item gnus-delay-initialize
+@findex gnus-delay-initialize
+By default, this function installs @code{gnus-delay-send-queue} in
+@code{gnus-get-new-news-hook}. But it accepts the optional second
+argument @code{no-check}. If it is non-@code{nil},
+@code{gnus-get-new-news-hook} is not changed. The optional first
+argument is ignored.
+
+For example, @code{(gnus-delay-initialize nil t)} means to do nothing.
+Presumably, you want to use the demon for sending due delayed articles.
+Just don't forget to set that up :-)
+@end table
+
+When delaying an article with @kbd{C-c C-j}, Message mode will
+automatically add a @code{"Date"} header with the current time. In
+many cases you probably want the @code{"Date"} header to reflect the
+time the message is sent instead. To do this, you have to delete
+@code{Date} from @code{message-draft-headers}.
+
+
+@node Marking Articles
+@section Marking Articles
+@cindex article marking
+@cindex article ticking
+@cindex marks
+
+There are several marks you can set on an article.
+
+You have marks that decide the @dfn{readedness} (whoo, neato-keano
+neologism ohoy!) of the article. Alphabetic marks generally mean
+@dfn{read}, while non-alphabetic characters generally mean @dfn{unread}.
+
+In addition, you also have marks that do not affect readedness.
+
+@ifinfo
+There's a plethora of commands for manipulating these marks.
+@end ifinfo
+
+@menu
+* Unread Articles:: Marks for unread articles.
+* Read Articles:: Marks for read articles.
+* Other Marks:: Marks that do not affect readedness.
+* Setting Marks:: How to set and remove marks.
+* Generic Marking Commands:: How to customize the marking.
+* Setting Process Marks:: How to mark articles for later processing.
+@end menu
+
+
+@node Unread Articles
+@subsection Unread Articles
+
+The following marks mark articles as (kinda) unread, in one form or
+other.
+
+@table @samp
+@item !
+@vindex gnus-ticked-mark
+Marked as ticked (@code{gnus-ticked-mark}).
+
+@dfn{Ticked articles} are articles that will remain visible always. If
+you see an article that you find interesting, or you want to put off
+reading it, or replying to it, until sometime later, you'd typically
+tick it. However, articles can be expired (from news servers by the
+news server software, Gnus itself never expires ticked messages), so if
+you want to keep an article forever, you'll have to make it persistent
+(@pxref{Persistent Articles}).
+
+@item ?
+@vindex gnus-dormant-mark
+Marked as dormant (@code{gnus-dormant-mark}).
+
+@dfn{Dormant articles} will only appear in the summary buffer if there
+are followups to it. If you want to see them even if they don't have
+followups, you can use the @kbd{/ D} command (@pxref{Limiting}).
+Otherwise (except for the visibility issue), they are just like ticked
+messages.
+
+@item SPACE
+@vindex gnus-unread-mark
+Marked as unread (@code{gnus-unread-mark}).
+
+@dfn{Unread articles} are articles that haven't been read at all yet.
+@end table
+
+
+@node Read Articles
+@subsection Read Articles
+@cindex expirable mark
+
+All the following marks mark articles as read.
+
+@table @samp
+
+@item r
+@vindex gnus-del-mark
+These are articles that the user has marked as read with the @kbd{d}
+command manually, more or less (@code{gnus-del-mark}).
+
+@item R
+@vindex gnus-read-mark
+Articles that have actually been read (@code{gnus-read-mark}).
+
+@item O
+@vindex gnus-ancient-mark
+Articles that were marked as read in previous sessions and are now
+@dfn{old} (@code{gnus-ancient-mark}).
+
+@item K
+@vindex gnus-killed-mark
+Marked as killed (@code{gnus-killed-mark}).
+
+@item X
+@vindex gnus-kill-file-mark
+Marked as killed by kill files (@code{gnus-kill-file-mark}).
+
+@item Y
+@vindex gnus-low-score-mark
+Marked as read by having too low a score (@code{gnus-low-score-mark}).
+
+@item C
+@vindex gnus-catchup-mark
+Marked as read by a catchup (@code{gnus-catchup-mark}).
+
+@item G
+@vindex gnus-canceled-mark
+Canceled article (@code{gnus-canceled-mark})
+
+@item Q
+@vindex gnus-sparse-mark
+Sparsely reffed article (@code{gnus-sparse-mark}). @xref{Customizing
+Threading}.
+
+@item M
+@vindex gnus-duplicate-mark
+Article marked as read by duplicate suppression
+(@code{gnus-duplicate-mark}). @xref{Duplicate Suppression}.
+
+@end table
+
+All these marks just mean that the article is marked as read, really.
+They are interpreted differently when doing adaptive scoring, though.
+
+One more special mark, though:
+
+@table @samp
+@item E
+@vindex gnus-expirable-mark
+Marked as expirable (@code{gnus-expirable-mark}).
+
+Marking articles as @dfn{expirable} (or have them marked as such
+automatically) doesn't make much sense in normal groups---a user doesn't
+control expiring of news articles, but in mail groups, for instance,
+articles marked as @dfn{expirable} can be deleted by Gnus at
+any time.
+@end table
+
+
+@node Other Marks
+@subsection Other Marks
+@cindex process mark
+@cindex bookmarks
+
+There are some marks that have nothing to do with whether the article is
+read or not.
+
+@itemize @bullet
+
+@item
+You can set a bookmark in the current article. Say you are reading a
+long thesis on cats' urinary tracts, and have to go home for dinner
+before you've finished reading the thesis. You can then set a bookmark
+in the article, and Gnus will jump to this bookmark the next time it
+encounters the article. @xref{Setting Marks}.
+
+@item
+@vindex gnus-replied-mark
+All articles that you have replied to or made a followup to (i.e., have
+answered) will be marked with an @samp{A} in the second column
+(@code{gnus-replied-mark}).
+
+@item
+@vindex gnus-forwarded-mark
+All articles that you have forwarded will be marked with an @samp{F} in
+the second column (@code{gnus-forwarded-mark}).
+
+@item
+@vindex gnus-cached-mark
+Articles stored in the article cache will be marked with an @samp{*} in
+the second column (@code{gnus-cached-mark}). @xref{Article Caching}.
+
+@item
+@vindex gnus-saved-mark
+Articles ``saved'' (in some manner or other; not necessarily
+religiously) are marked with an @samp{S} in the second column
+(@code{gnus-saved-mark}).
+
+@item
+@vindex gnus-unseen-mark
+Articles that haven't been seen before in Gnus by the user are marked
+with a @samp{.} in the second column (@code{gnus-unseen-mark}).
+
+@item
+@vindex gnus-downloaded-mark
+When using the Gnus agent (@pxref{Agent Basics}), articles may be
+downloaded for unplugged (offline) viewing. If you are using the
+@samp{%O} spec, these articles get the @samp{+} mark in that spec.
+(The variable @code{gnus-downloaded-mark} controls which character to
+use.)
+
+@item
+@vindex gnus-undownloaded-mark
+When using the Gnus agent (@pxref{Agent Basics}), some articles might
+not have been downloaded. Such articles cannot be viewed while you
+are unplugged (offline). If you are using the @samp{%O} spec, these
+articles get the @samp{-} mark in that spec. (The variable
+@code{gnus-undownloaded-mark} controls which character to use.)
+
+@item
+@vindex gnus-downloadable-mark
+The Gnus agent (@pxref{Agent Basics}) downloads some articles
+automatically, but it is also possible to explicitly mark articles for
+download, even if they would not be downloaded automatically. Such
+explicitly-marked articles get the @samp{%} mark in the first column.
+(The variable @code{gnus-downloadable-mark} controls which character to
+use.)
+
+@item
+@vindex gnus-not-empty-thread-mark
+@vindex gnus-empty-thread-mark
+If the @samp{%e} spec is used, the presence of threads or not will be
+marked with @code{gnus-not-empty-thread-mark} and
+@code{gnus-empty-thread-mark} in the third column, respectively.
+
+@item
+@vindex gnus-process-mark
+Finally we have the @dfn{process mark} (@code{gnus-process-mark}). A
+variety of commands react to the presence of the process mark. For
+instance, @kbd{X u} (@code{gnus-uu-decode-uu}) will uudecode and view
+all articles that have been marked with the process mark. Articles
+marked with the process mark have a @samp{#} in the second column.
+
+@end itemize
+
+You might have noticed that most of these ``non-readedness'' marks
+appear in the second column by default. So if you have a cached, saved,
+replied article that you have process-marked, what will that look like?
+
+Nothing much. The precedence rules go as follows: process -> cache ->
+replied -> saved. So if the article is in the cache and is replied,
+you'll only see the cache mark and not the replied mark.
+
+
+@node Setting Marks
+@subsection Setting Marks
+@cindex setting marks
+
+All the marking commands understand the numeric prefix.
+
+@table @kbd
+@item M c
+@itemx M-u
+@kindex M c (Summary)
+@kindex M-u (Summary)
+@findex gnus-summary-clear-mark-forward
+@cindex mark as unread
+Clear all readedness-marks from the current article
+(@code{gnus-summary-clear-mark-forward}). In other words, mark the
+article as unread.
+
+@item M t
+@itemx !
+@kindex ! (Summary)
+@kindex M t (Summary)
+@findex gnus-summary-tick-article-forward
+Tick the current article (@code{gnus-summary-tick-article-forward}).
+@xref{Article Caching}.
+
+@item M ?
+@itemx ?
+@kindex ? (Summary)
+@kindex M ? (Summary)
+@findex gnus-summary-mark-as-dormant
+Mark the current article as dormant
+(@code{gnus-summary-mark-as-dormant}). @xref{Article Caching}.
+
+@item M d
+@itemx d
+@kindex M d (Summary)
+@kindex d (Summary)
+@findex gnus-summary-mark-as-read-forward
+Mark the current article as read
+(@code{gnus-summary-mark-as-read-forward}).
+
+@item D
+@kindex D (Summary)
+@findex gnus-summary-mark-as-read-backward
+Mark the current article as read and move point to the previous line
+(@code{gnus-summary-mark-as-read-backward}).
+
+@item M k
+@itemx k
+@kindex k (Summary)
+@kindex M k (Summary)
+@findex gnus-summary-kill-same-subject-and-select
+Mark all articles that have the same subject as the current one as read,
+and then select the next unread article
+(@code{gnus-summary-kill-same-subject-and-select}).
+
+@item M K
+@itemx C-k
+@kindex M K (Summary)
+@kindex C-k (Summary)
+@findex gnus-summary-kill-same-subject
+Mark all articles that have the same subject as the current one as read
+(@code{gnus-summary-kill-same-subject}).
+
+@item M C
+@kindex M C (Summary)
+@findex gnus-summary-catchup
+@c @icon{gnus-summary-catchup}
+Mark all unread articles as read (@code{gnus-summary-catchup}).
+
+@item M C-c
+@kindex M C-c (Summary)
+@findex gnus-summary-catchup-all
+Mark all articles in the group as read---even the ticked and dormant
+articles (@code{gnus-summary-catchup-all}).
+
+@item M H
+@kindex M H (Summary)
+@findex gnus-summary-catchup-to-here
+Catchup the current group to point (before the point)
+(@code{gnus-summary-catchup-to-here}).
+
+@item M h
+@kindex M h (Summary)
+@findex gnus-summary-catchup-from-here
+Catchup the current group from point (after the point)
+(@code{gnus-summary-catchup-from-here}).
+
+@item C-w
+@kindex C-w (Summary)
+@findex gnus-summary-mark-region-as-read
+Mark all articles between point and mark as read
+(@code{gnus-summary-mark-region-as-read}).
+
+@item M V k
+@kindex M V k (Summary)
+@findex gnus-summary-kill-below
+Kill all articles with scores below the default score (or below the
+numeric prefix) (@code{gnus-summary-kill-below}).
+
+@item M e
+@itemx E
+@kindex M e (Summary)
+@kindex E (Summary)
+@findex gnus-summary-mark-as-expirable
+Mark the current article as expirable
+(@code{gnus-summary-mark-as-expirable}).
+
+@item M b
+@kindex M b (Summary)
+@findex gnus-summary-set-bookmark
+Set a bookmark in the current article
+(@code{gnus-summary-set-bookmark}).
+
+@item M B
+@kindex M B (Summary)
+@findex gnus-summary-remove-bookmark
+Remove the bookmark from the current article
+(@code{gnus-summary-remove-bookmark}).
+
+@item M V c
+@kindex M V c (Summary)
+@findex gnus-summary-clear-above
+Clear all marks from articles with scores over the default score (or
+over the numeric prefix) (@code{gnus-summary-clear-above}).
+
+@item M V u
+@kindex M V u (Summary)
+@findex gnus-summary-tick-above
+Tick all articles with scores over the default score (or over the
+numeric prefix) (@code{gnus-summary-tick-above}).
+
+@item M V m
+@kindex M V m (Summary)
+@findex gnus-summary-mark-above
+Prompt for a mark, and mark all articles with scores over the default
+score (or over the numeric prefix) with this mark
+(@code{gnus-summary-clear-above}).
+@end table
+
+@vindex gnus-summary-goto-unread
+The @code{gnus-summary-goto-unread} variable controls what action should
+be taken after setting a mark. If non-@code{nil}, point will move to
+the next/previous unread article. If @code{nil}, point will just move
+one line up or down. As a special case, if this variable is
+@code{never}, all the marking commands as well as other commands (like
+@kbd{SPACE}) will move to the next article, whether it is unread or not.
+The default is @code{t}.
+
+
+@node Generic Marking Commands
+@subsection Generic Marking Commands
+
+Some people would like the command that ticks an article (@kbd{!}) to
+go to the next article. Others would like it to go to the next unread
+article. Yet others would like it to stay on the current article.
+And even though I haven't heard of anybody wanting it to go to the
+previous (unread) article, I'm sure there are people that want that as
+well.
+
+Multiply these five behaviors with five different marking commands, and
+you get a potentially complex set of variable to control what each
+command should do.
+
+To sidestep that mess, Gnus provides commands that do all these
+different things. They can be found on the @kbd{M M} map in the summary
+buffer. Type @kbd{M M C-h} to see them all---there are too many of them
+to list in this manual.
+
+While you can use these commands directly, most users would prefer
+altering the summary mode keymap. For instance, if you would like the
+@kbd{!} command to go to the next article instead of the next unread
+article, you could say something like:
+
+@lisp
+@group
+(add-hook 'gnus-summary-mode-hook 'my-alter-summary-map)
+(defun my-alter-summary-map ()
+ (local-set-key "!" 'gnus-summary-put-mark-as-ticked-next))
+@end group
+@end lisp
+
+@noindent
+or
+
+@lisp
+(defun my-alter-summary-map ()
+ (local-set-key "!" "MM!n"))
+@end lisp
+
+
+@node Setting Process Marks
+@subsection Setting Process Marks
+@cindex setting process marks
+
+Process marks are displayed as @code{#} in the summary buffer, and are
+used for marking articles in such a way that other commands will
+process these articles. For instance, if you process mark four
+articles and then use the @kbd{*} command, Gnus will enter these four
+articles into the cache. For more information,
+@pxref{Process/Prefix}.
+
+@table @kbd
+
+@item M P p
+@itemx #
+@kindex # (Summary)
+@kindex M P p (Summary)
+@findex gnus-summary-mark-as-processable
+Mark the current article with the process mark
+(@code{gnus-summary-mark-as-processable}).
+@findex gnus-summary-unmark-as-processable
+
+@item M P u
+@itemx M-#
+@kindex M P u (Summary)
+@kindex M-# (Summary)
+Remove the process mark, if any, from the current article
+(@code{gnus-summary-unmark-as-processable}).
+
+@item M P U
+@kindex M P U (Summary)
+@findex gnus-summary-unmark-all-processable
+Remove the process mark from all articles
+(@code{gnus-summary-unmark-all-processable}).
+
+@item M P i
+@kindex M P i (Summary)
+@findex gnus-uu-invert-processable
+Invert the list of process marked articles
+(@code{gnus-uu-invert-processable}).
+
+@item M P R
+@kindex M P R (Summary)
+@findex gnus-uu-mark-by-regexp
+Mark articles that have a @code{Subject} header that matches a regular
+expression (@code{gnus-uu-mark-by-regexp}).
+
+@item M P G
+@kindex M P G (Summary)
+@findex gnus-uu-unmark-by-regexp
+Unmark articles that have a @code{Subject} header that matches a regular
+expression (@code{gnus-uu-unmark-by-regexp}).
+
+@item M P r
+@kindex M P r (Summary)
+@findex gnus-uu-mark-region
+Mark articles in region (@code{gnus-uu-mark-region}).
+
+@item M P g
+@kindex M P g (Summary)
+@findex gnus-uu-unmark-region
+Unmark articles in region (@code{gnus-uu-unmark-region}).
+
+@item M P t
+@kindex M P t (Summary)
+@findex gnus-uu-mark-thread
+Mark all articles in the current (sub)thread
+(@code{gnus-uu-mark-thread}).
+
+@item M P T
+@kindex M P T (Summary)
+@findex gnus-uu-unmark-thread
+Unmark all articles in the current (sub)thread
+(@code{gnus-uu-unmark-thread}).
+
+@item M P v
+@kindex M P v (Summary)
+@findex gnus-uu-mark-over
+Mark all articles that have a score above the prefix argument
+(@code{gnus-uu-mark-over}).
+
+@item M P s
+@kindex M P s (Summary)
+@findex gnus-uu-mark-series
+Mark all articles in the current series (@code{gnus-uu-mark-series}).
+
+@item M P S
+@kindex M P S (Summary)
+@findex gnus-uu-mark-sparse
+Mark all series that have already had some articles marked
+(@code{gnus-uu-mark-sparse}).
+
+@item M P a
+@kindex M P a (Summary)
+@findex gnus-uu-mark-all
+Mark all articles in series order (@code{gnus-uu-mark-all}).
+
+@item M P b
+@kindex M P b (Summary)
+@findex gnus-uu-mark-buffer
+Mark all articles in the buffer in the order they appear
+(@code{gnus-uu-mark-buffer}).
+
+@item M P k
+@kindex M P k (Summary)
+@findex gnus-summary-kill-process-mark
+Push the current process mark set onto the stack and unmark all articles
+(@code{gnus-summary-kill-process-mark}).
+
+@item M P y
+@kindex M P y (Summary)
+@findex gnus-summary-yank-process-mark
+Pop the previous process mark set from the stack and restore it
+(@code{gnus-summary-yank-process-mark}).
+
+@item M P w
+@kindex M P w (Summary)
+@findex gnus-summary-save-process-mark
+Push the current process mark set onto the stack
+(@code{gnus-summary-save-process-mark}).
+
+@end table
+
+Also see the @kbd{&} command in @ref{Searching for Articles}, for how to
+set process marks based on article body contents.
+
+
+@node Limiting
+@section Limiting
+@cindex limiting
+
+It can be convenient to limit the summary buffer to just show some
+subset of the articles currently in the group. The effect most limit
+commands have is to remove a few (or many) articles from the summary
+buffer.
+
+Limiting commands work on subsets of the articles already fetched from
+the servers. These commands don't query the server for additional
+articles.
+
+@table @kbd
+
+@item / /
+@itemx / s
+@kindex / / (Summary)
+@findex gnus-summary-limit-to-subject
+Limit the summary buffer to articles that match some subject
+(@code{gnus-summary-limit-to-subject}). If given a prefix, exclude
+matching articles.
+
+@item / a
+@kindex / a (Summary)
+@findex gnus-summary-limit-to-author
+Limit the summary buffer to articles that match some author
+(@code{gnus-summary-limit-to-author}). If given a prefix, exclude
+matching articles.
+
+@item / R
+@kindex / R (Summary)
+@findex gnus-summary-limit-to-recipient
+Limit the summary buffer to articles that match some recipient
+(@code{gnus-summary-limit-to-recipient}). If given a prefix, exclude
+matching articles.
+
+@item / A
+@kindex / A (Summary)
+@findex gnus-summary-limit-to-address
+Limit the summary buffer to articles in which contents of From, To or Cc
+header match a given address (@code{gnus-summary-limit-to-address}). If
+given a prefix, exclude matching articles.
+
+@item / S
+@kindex / S (Summary)
+@findex gnus-summary-limit-to-singletons
+Limit the summary buffer to articles that aren't part of any displayed
+threads (@code{gnus-summary-limit-to-singletons}). If given a prefix,
+limit to articles that are part of displayed threads.
+
+@item / x
+@kindex / x (Summary)
+@findex gnus-summary-limit-to-extra
+Limit the summary buffer to articles that match one of the ``extra''
+headers (@pxref{To From Newsgroups})
+(@code{gnus-summary-limit-to-extra}). If given a prefix, exclude
+matching articles.
+
+@item / u
+@itemx x
+@kindex / u (Summary)
+@kindex x (Summary)
+@findex gnus-summary-limit-to-unread
+Limit the summary buffer to articles not marked as read
+(@code{gnus-summary-limit-to-unread}). If given a prefix, limit the
+buffer to articles strictly unread. This means that ticked and
+dormant articles will also be excluded.
+
+@item / m
+@kindex / m (Summary)
+@findex gnus-summary-limit-to-marks
+Ask for a mark and then limit to all articles that have been marked
+with that mark (@code{gnus-summary-limit-to-marks}).
+
+@item / t
+@kindex / t (Summary)
+@findex gnus-summary-limit-to-age
+Ask for a number and then limit the summary buffer to articles older than (or equal to) that number of days
+(@code{gnus-summary-limit-to-age}). If given a prefix, limit to
+articles younger than that number of days.
+
+@item / n
+@kindex / n (Summary)
+@findex gnus-summary-limit-to-articles
+With prefix @samp{n}, limit the summary buffer to the next @samp{n}
+articles. If not given a prefix, use the process marked articles
+instead. (@code{gnus-summary-limit-to-articles}).
+
+@item / w
+@kindex / w (Summary)
+@findex gnus-summary-pop-limit
+Pop the previous limit off the stack and restore it
+(@code{gnus-summary-pop-limit}). If given a prefix, pop all limits off
+the stack.
+
+@item / .
+@kindex / . (Summary)
+@findex gnus-summary-limit-to-unseen
+Limit the summary buffer to the unseen articles
+(@code{gnus-summary-limit-to-unseen}).
+
+@item / v
+@kindex / v (Summary)
+@findex gnus-summary-limit-to-score
+Limit the summary buffer to articles that have a score at or above some
+score (@code{gnus-summary-limit-to-score}).
+
+@item / p
+@kindex / p (Summary)
+@findex gnus-summary-limit-to-display-predicate
+Limit the summary buffer to articles that satisfy the @code{display}
+group parameter predicate
+(@code{gnus-summary-limit-to-display-predicate}). @xref{Group
+Parameters}, for more on this predicate.
+
+@item / r
+@kindex / r (Summary)
+@findex gnus-summary-limit-to-replied
+Limit the summary buffer to replied articles
+(@code{gnus-summary-limit-to-replied}). If given a prefix, exclude
+replied articles.
+
+@item / E
+@itemx M S
+@kindex M S (Summary)
+@kindex / E (Summary)
+@findex gnus-summary-limit-include-expunged
+Include all expunged articles in the limit
+(@code{gnus-summary-limit-include-expunged}).
+
+@item / D
+@kindex / D (Summary)
+@findex gnus-summary-limit-include-dormant
+Include all dormant articles in the limit
+(@code{gnus-summary-limit-include-dormant}).
+
+@item / *
+@kindex / * (Summary)
+@findex gnus-summary-limit-include-cached
+Include all cached articles in the limit
+(@code{gnus-summary-limit-include-cached}).
+
+@item / d
+@kindex / d (Summary)
+@findex gnus-summary-limit-exclude-dormant
+Exclude all dormant articles from the limit
+(@code{gnus-summary-limit-exclude-dormant}).
+
+@item / M
+@kindex / M (Summary)
+@findex gnus-summary-limit-exclude-marks
+Exclude all marked articles (@code{gnus-summary-limit-exclude-marks}).
+
+@item / T
+@kindex / T (Summary)
+@findex gnus-summary-limit-include-thread
+Include all the articles in the current thread in the limit.
+
+@item / c
+@kindex / c (Summary)
+@findex gnus-summary-limit-exclude-childless-dormant
+Exclude all dormant articles that have no children from the limit@*
+(@code{gnus-summary-limit-exclude-childless-dormant}).
+
+@item / C
+@kindex / C (Summary)
+@findex gnus-summary-limit-mark-excluded-as-read
+Mark all excluded unread articles as read
+(@code{gnus-summary-limit-mark-excluded-as-read}). If given a prefix,
+also mark excluded ticked and dormant articles as read.
+
+@item / b
+@kindex / b (Summary)
+@findex gnus-summary-limit-to-bodies
+Limit the summary buffer to articles that have bodies that match a
+certain regexp (@code{gnus-summary-limit-to-bodies}). If given a
+prefix, reverse the limit. This command is quite slow since it
+requires selecting each article to find the matches.
+
+@item / h
+@kindex / h (Summary)
+@findex gnus-summary-limit-to-headers
+Like the previous command, only limit to headers instead
+(@code{gnus-summary-limit-to-headers}).
+
+@end table
+
+
+The following commands aren't limiting commands, but use the @kbd{/}
+prefix as well.
+
+@table @kbd
+@item / N
+@kindex / N (Summary)
+@findex gnus-summary-insert-new-articles
+Insert all new articles in the summary buffer. It scans for new emails
+if @var{back-end}@code{-get-new-mail} is non-@code{nil}.
+
+@item / o
+@kindex / o (Summary)
+@findex gnus-summary-insert-old-articles
+Insert all old articles in the summary buffer. If given a numbered
+prefix, fetch this number of articles.
+
+@end table
+
+
+@node Threading
+@section Threading
+@cindex threading
+@cindex article threading
+
+Gnus threads articles by default. @dfn{To thread} is to put responses
+to articles directly after the articles they respond to---in a
+hierarchical fashion.
+
+Threading is done by looking at the @code{References} headers of the
+articles. In a perfect world, this would be enough to build pretty
+trees, but unfortunately, the @code{References} header is often broken
+or simply missing. Weird news propagation exacerbates the problem,
+so one has to employ other heuristics to get pleasing results. A
+plethora of approaches exists, as detailed in horrible detail in
+@ref{Customizing Threading}.
+
+First, a quick overview of the concepts:
+
+@table @dfn
+@item root
+The top-most article in a thread; the first article in the thread.
+
+@item thread
+A tree-like article structure.
+
+@item sub-thread
+A small(er) section of this tree-like structure.
+
+@item loose threads
+Threads often lose their roots due to article expiry, or due to the root
+already having been read in a previous session, and not displayed in the
+summary buffer. We then typically have many sub-threads that really
+belong to one thread, but are without connecting roots. These are
+called loose threads.
+
+@item thread gathering
+An attempt to gather loose threads into bigger threads.
+
+@item sparse threads
+A thread where the missing articles have been ``guessed'' at, and are
+displayed as empty lines in the summary buffer.
+
+@end table
+
+
+@menu
+* Customizing Threading:: Variables you can change to affect the threading.
+* Thread Commands:: Thread based commands in the summary buffer.
+@end menu
+
+
+@node Customizing Threading
+@subsection Customizing Threading
+@cindex customizing threading
+
+@menu
+* Loose Threads:: How Gnus gathers loose threads into bigger threads.
+* Filling In Threads:: Making the threads displayed look fuller.
+* More Threading:: Even more variables for fiddling with threads.
+* Low-Level Threading:: You thought it was over@dots{} but you were wrong!
+@end menu
+
+
+@node Loose Threads
+@subsubsection Loose Threads
+@cindex <
+@cindex >
+@cindex loose threads
+
+@table @code
+@item gnus-summary-make-false-root
+@vindex gnus-summary-make-false-root
+If non-@code{nil}, Gnus will gather all loose subtrees into one big tree
+and create a dummy root at the top. (Wait a minute. Root at the top?
+Yup.) Loose subtrees occur when the real root has expired, or you've
+read or killed the root in a previous session.
+
+When there is no real root of a thread, Gnus will have to fudge
+something. This variable says what fudging method Gnus should use.
+There are four possible values:
+
+@iftex
+@iflatex
+\gnusfigure{The Summary Buffer}{390}{
+\put(0,0){\epsfig{figure=ps/summary-adopt,width=7.5cm}}
+\put(445,0){\makebox(0,0)[br]{\epsfig{figure=ps/summary-empty,width=7.5cm}}}
+\put(0,400){\makebox(0,0)[tl]{\epsfig{figure=ps/summary-none,width=7.5cm}}}
+\put(445,400){\makebox(0,0)[tr]{\epsfig{figure=ps/summary-dummy,width=7.5cm}}}
+}
+@end iflatex
+@end iftex
+
+@cindex adopting articles
+
+@table @code
+
+@item adopt
+Gnus will make the first of the orphaned articles the parent. This
+parent will adopt all the other articles. The adopted articles will be
+marked as such by pointy brackets (@samp{<>}) instead of the standard
+square brackets (@samp{[]}). This is the default method.
+
+@item dummy
+@vindex gnus-summary-dummy-line-format
+@vindex gnus-summary-make-false-root-always
+Gnus will create a dummy summary line that will pretend to be the
+parent. This dummy line does not correspond to any real article, so
+selecting it will just select the first real article after the dummy
+article. @code{gnus-summary-dummy-line-format} is used to specify the
+format of the dummy roots. It accepts only one format spec: @samp{S},
+which is the subject of the article. @xref{Formatting Variables}.
+If you want all threads to have a dummy root, even the non-gathered
+ones, set @code{gnus-summary-make-false-root-always} to @code{t}.
+
+@item empty
+Gnus won't actually make any article the parent, but simply leave the
+subject field of all orphans except the first empty. (Actually, it will
+use @code{gnus-summary-same-subject} as the subject (@pxref{Summary
+Buffer Format}).)
+
+@item none
+Don't make any article parent at all. Just gather the threads and
+display them after one another.
+
+@item nil
+Don't gather loose threads.
+@end table
+
+@item gnus-summary-gather-subject-limit
+@vindex gnus-summary-gather-subject-limit
+Loose threads are gathered by comparing subjects of articles. If this
+variable is @code{nil}, Gnus requires an exact match between the
+subjects of the loose threads before gathering them into one big
+super-thread. This might be too strict a requirement, what with the
+presence of stupid newsreaders that chop off long subject lines. If
+you think so, set this variable to, say, 20 to require that only the
+first 20 characters of the subjects have to match. If you set this
+variable to a really low number, you'll find that Gnus will gather
+everything in sight into one thread, which isn't very helpful.
+
+@cindex fuzzy article gathering
+If you set this variable to the special value @code{fuzzy}, Gnus will
+use a fuzzy string comparison algorithm on the subjects (@pxref{Fuzzy
+Matching}).
+
+@item gnus-simplify-subject-fuzzy-regexp
+@vindex gnus-simplify-subject-fuzzy-regexp
+This can either be a regular expression or list of regular expressions
+that match strings that will be removed from subjects if fuzzy subject
+simplification is used.
+
+@item gnus-simplify-ignored-prefixes
+@vindex gnus-simplify-ignored-prefixes
+If you set @code{gnus-summary-gather-subject-limit} to something as low
+as 10, you might consider setting this variable to something sensible:
+
+@c Written by Michael Ernst <mernst@cs.rice.edu>
+@lisp
+(setq gnus-simplify-ignored-prefixes
+ (concat
+ "\\`\\[?\\("
+ (mapconcat
+ 'identity
+ '("looking"
+ "wanted" "followup" "summary\\( of\\)?"
+ "help" "query" "problem" "question"
+ "answer" "reference" "announce"
+ "How can I" "How to" "Comparison of"
+ ;; ...
+ )
+ "\\|")
+ "\\)\\s *\\("
+ (mapconcat 'identity
+ '("for" "for reference" "with" "about")
+ "\\|")
+ "\\)?\\]?:?[ \t]*"))
+@end lisp
+
+All words that match this regexp will be removed before comparing two
+subjects.
+
+@item gnus-simplify-subject-functions
+@vindex gnus-simplify-subject-functions
+If non-@code{nil}, this variable overrides
+@code{gnus-summary-gather-subject-limit}. This variable should be a
+list of functions to apply to the @code{Subject} string iteratively to
+arrive at the simplified version of the string.
+
+Useful functions to put in this list include:
+
+@table @code
+@item gnus-simplify-subject-re
+@findex gnus-simplify-subject-re
+Strip the leading @samp{Re:}.
+
+@item gnus-simplify-subject-fuzzy
+@findex gnus-simplify-subject-fuzzy
+Simplify fuzzily.
+
+@item gnus-simplify-whitespace
+@findex gnus-simplify-whitespace
+Remove excessive whitespace.
+
+@item gnus-simplify-all-whitespace
+@findex gnus-simplify-all-whitespace
+Remove all whitespace.
+@end table
+
+You may also write your own functions, of course.
+
+
+@item gnus-summary-gather-exclude-subject
+@vindex gnus-summary-gather-exclude-subject
+Since loose thread gathering is done on subjects only, that might lead
+to many false hits, especially with certain common subjects like
+@samp{} and @samp{(none)}. To make the situation slightly better,
+you can use the regexp @code{gnus-summary-gather-exclude-subject} to say
+what subjects should be excluded from the gathering process.@*
+The default is @samp{^ *$\\|^(none)$}.
+
+@item gnus-summary-thread-gathering-function
+@vindex gnus-summary-thread-gathering-function
+Gnus gathers threads by looking at @code{Subject} headers. This means
+that totally unrelated articles may end up in the same ``thread'', which
+is confusing. An alternate approach is to look at all the
+@code{Message-ID}s in all the @code{References} headers to find matches.
+This will ensure that no gathered threads ever include unrelated
+articles, but it also means that people who have posted with broken
+newsreaders won't be gathered properly. The choice is yours---plague or
+cholera:
+
+@table @code
+@item gnus-gather-threads-by-subject
+@findex gnus-gather-threads-by-subject
+This function is the default gathering function and looks at
+@code{Subject}s exclusively.
+
+@item gnus-gather-threads-by-references
+@findex gnus-gather-threads-by-references
+This function looks at @code{References} headers exclusively.
+@end table
+
+If you want to test gathering by @code{References}, you could say
+something like:
+
+@lisp
+(setq gnus-summary-thread-gathering-function
+ 'gnus-gather-threads-by-references)
+@end lisp
+
+@end table
+
+
+@node Filling In Threads
+@subsubsection Filling In Threads
+
+@table @code
+@item gnus-fetch-old-headers
+@vindex gnus-fetch-old-headers
+If non-@code{nil}, Gnus will attempt to build old threads by fetching
+more old headers---headers to articles marked as read. If you would
+like to display as few summary lines as possible, but still connect as
+many loose threads as possible, you should set this variable to
+@code{some} or a number. If you set it to a number, no more than that
+number of extra old headers will be fetched. In either case, fetching
+old headers only works if the back end you are using carries overview
+files---this would normally be @code{nntp}, @code{nnspool},
+@code{nnml}, and @code{nnmaildir}. Also remember that if the root of
+the thread has been expired by the server, there's not much Gnus can
+do about that.
+
+This variable can also be set to @code{invisible}. This won't have any
+visible effects, but is useful if you use the @kbd{A T} command a lot
+(@pxref{Finding the Parent}).
+
+The server has to support @acronym{NOV} for any of this to work.
+
+@cindex Gmane, gnus-fetch-old-headers
+This feature can seriously impact performance it ignores all locally
+cached header entries. Setting it to @code{t} for groups for a server
+that doesn't expire articles (such as news.gmane.org), leads to very
+slow summary generation.
+
+@item gnus-fetch-old-ephemeral-headers
+@vindex gnus-fetch-old-ephemeral-headers
+Same as @code{gnus-fetch-old-headers}, but only used for ephemeral
+newsgroups.
+
+@item gnus-build-sparse-threads
+@vindex gnus-build-sparse-threads
+Fetching old headers can be slow. A low-rent similar effect can be
+gotten by setting this variable to @code{some}. Gnus will then look at
+the complete @code{References} headers of all articles and try to string
+together articles that belong in the same thread. This will leave
+@dfn{gaps} in the threading display where Gnus guesses that an article
+is missing from the thread. (These gaps appear like normal summary
+lines. If you select a gap, Gnus will try to fetch the article in
+question.) If this variable is @code{t}, Gnus will display all these
+``gaps'' without regard for whether they are useful for completing the
+thread or not. Finally, if this variable is @code{more}, Gnus won't cut
+off sparse leaf nodes that don't lead anywhere. This variable is
+@code{nil} by default.
+
+@item gnus-read-all-available-headers
+@vindex gnus-read-all-available-headers
+This is a rather obscure variable that few will find useful. It's
+intended for those non-news newsgroups where the back end has to fetch
+quite a lot to present the summary buffer, and where it's impossible to
+go back to parents of articles. This is mostly the case in the
+web-based groups.
+
+If you don't use those, then it's safe to leave this as the default
+@code{nil}. If you want to use this variable, it should be a regexp
+that matches the group name, or @code{t} for all groups.
+
+@end table
+
+
+@node More Threading
+@subsubsection More Threading
+
+@table @code
+@item gnus-show-threads
+@vindex gnus-show-threads
+If this variable is @code{nil}, no threading will be done, and all of
+the rest of the variables here will have no effect. Turning threading
+off will speed group selection up a bit, but it is sure to make reading
+slower and more awkward.
+
+@item gnus-thread-hide-subtree
+@vindex gnus-thread-hide-subtree
+If non-@code{nil}, all threads will be hidden when the summary buffer is
+generated.
+
+This can also be a predicate specifier (@pxref{Predicate Specifiers}).
+Available predicates are @code{gnus-article-unread-p} and
+@code{gnus-article-unseen-p}.
+
+Here's an example:
+
+@lisp
+(setq gnus-thread-hide-subtree
+ '(or gnus-article-unread-p
+ gnus-article-unseen-p))
+@end lisp
+
+(It's a pretty nonsensical example, since all unseen articles are also
+unread, but you get my drift.)
+
+
+@item gnus-thread-expunge-below
+@vindex gnus-thread-expunge-below
+All threads that have a total score (as defined by
+@code{gnus-thread-score-function}) less than this number will be
+expunged. This variable is @code{nil} by default, which means that no
+threads are expunged.
+
+@item gnus-thread-hide-killed
+@vindex gnus-thread-hide-killed
+if you kill a thread and this variable is non-@code{nil}, the subtree
+will be hidden.
+
+@item gnus-thread-ignore-subject
+@vindex gnus-thread-ignore-subject
+Sometimes somebody changes the subject in the middle of a thread. If
+this variable is non-@code{nil}, which is the default, the subject
+change is ignored. If it is @code{nil}, a change in the subject will
+result in a new thread.
+
+@item gnus-thread-indent-level
+@vindex gnus-thread-indent-level
+This is a number that says how much each sub-thread should be indented.
+The default is 4.
+
+@item gnus-sort-gathered-threads-function
+@vindex gnus-sort-gathered-threads-function
+Sometimes, particularly with mailing lists, the order in which mails
+arrive locally is not necessarily the same as the order in which they
+arrived on the mailing list. Consequently, when sorting sub-threads
+using the default @code{gnus-thread-sort-by-number}, responses can end
+up appearing before the article to which they are responding to.
+Setting this variable to an alternate value
+(e.g., @code{gnus-thread-sort-by-date}), in a group's parameters or in an
+appropriate hook (e.g., @code{gnus-summary-generate-hook}) can produce a
+more logical sub-thread ordering in such instances.
+
+@end table
+
+
+@node Low-Level Threading
+@subsubsection Low-Level Threading
+
+@table @code
+
+@item gnus-parse-headers-hook
+@vindex gnus-parse-headers-hook
+Hook run before parsing any headers.
+
+@item gnus-alter-header-function
+@vindex gnus-alter-header-function
+If non-@code{nil}, this function will be called to allow alteration of
+article header structures. The function is called with one parameter,
+the article header vector, which it may alter in any way. For instance,
+if you have a mail-to-news gateway which alters the @code{Message-ID}s
+in systematic ways (by adding prefixes and such), you can use this
+variable to un-scramble the @code{Message-ID}s so that they are more
+meaningful. Here's one example:
+
+@lisp
+(setq gnus-alter-header-function 'my-alter-message-id)
+
+(defun my-alter-message-id (header)
+ (let ((id (mail-header-id header)))
+ (when (string-match
+ "\\(<[^<>@@]*\\)\\.?cygnus\\..*@@\\([^<>@@]*>\\)" id)
+ (mail-header-set-id
+ (concat (match-string 1 id) "@@" (match-string 2 id))
+ header))))
+@end lisp
+
+@end table
+
+
+@node Thread Commands
+@subsection Thread Commands
+@cindex thread commands
+
+@table @kbd
+
+@item T k
+@itemx C-M-k
+@kindex T k (Summary)
+@kindex C-M-k (Summary)
+@findex gnus-summary-kill-thread
+Mark all articles in the current (sub-)thread as read
+(@code{gnus-summary-kill-thread}). If the prefix argument is positive,
+remove all marks instead. If the prefix argument is negative, tick
+articles instead.
+
+@item T l
+@itemx C-M-l
+@kindex T l (Summary)
+@kindex C-M-l (Summary)
+@findex gnus-summary-lower-thread
+Lower the score of the current (sub-)thread
+(@code{gnus-summary-lower-thread}).
+
+@item T i
+@kindex T i (Summary)
+@findex gnus-summary-raise-thread
+Increase the score of the current (sub-)thread
+(@code{gnus-summary-raise-thread}).
+
+@item T #
+@kindex T # (Summary)
+@findex gnus-uu-mark-thread
+Set the process mark on the current (sub-)thread
+(@code{gnus-uu-mark-thread}).
+
+@item T M-#
+@kindex T M-# (Summary)
+@findex gnus-uu-unmark-thread
+Remove the process mark from the current (sub-)thread
+(@code{gnus-uu-unmark-thread}).
+
+@item T T
+@kindex T T (Summary)
+@findex gnus-summary-toggle-threads
+Toggle threading (@code{gnus-summary-toggle-threads}).
+
+@item T s
+@kindex T s (Summary)
+@findex gnus-summary-show-thread
+Expose the (sub-)thread hidden under the current article, if any@*
+(@code{gnus-summary-show-thread}).
+
+@item T h
+@kindex T h (Summary)
+@findex gnus-summary-hide-thread
+Hide the current (sub-)thread (@code{gnus-summary-hide-thread}).
+
+@item T S
+@kindex T S (Summary)
+@findex gnus-summary-show-all-threads
+Expose all hidden threads (@code{gnus-summary-show-all-threads}).
+
+@item T H
+@kindex T H (Summary)
+@findex gnus-summary-hide-all-threads
+Hide all threads (@code{gnus-summary-hide-all-threads}).
+
+@item T t
+@kindex T t (Summary)
+@findex gnus-summary-rethread-current
+Re-thread the current article's thread
+(@code{gnus-summary-rethread-current}). This works even when the
+summary buffer is otherwise unthreaded.
+
+@item T ^
+@kindex T ^ (Summary)
+@findex gnus-summary-reparent-thread
+Make the current article the child of the marked (or previous) article
+(@code{gnus-summary-reparent-thread}).
+
+@item T M-^
+@kindex T M-^ (Summary)
+@findex gnus-summary-reparent-children
+Make the current article the parent of the marked articles
+(@code{gnus-summary-reparent-children}).
+
+@end table
+
+The following commands are thread movement commands. They all
+understand the numeric prefix.
+
+@table @kbd
+
+@item T n
+@kindex T n (Summary)
+@itemx C-M-f
+@kindex C-M-n (Summary)
+@itemx M-down
+@kindex M-down (Summary)
+@findex gnus-summary-next-thread
+Go to the next thread (@code{gnus-summary-next-thread}).
+
+@item T p
+@kindex T p (Summary)
+@itemx C-M-b
+@kindex C-M-p (Summary)
+@itemx M-up
+@kindex M-up (Summary)
+@findex gnus-summary-prev-thread
+Go to the previous thread (@code{gnus-summary-prev-thread}).
+
+@item T d
+@kindex T d (Summary)
+@findex gnus-summary-down-thread
+Descend the thread (@code{gnus-summary-down-thread}).
+
+@item T u
+@kindex T u (Summary)
+@findex gnus-summary-up-thread
+Ascend the thread (@code{gnus-summary-up-thread}).
+
+@item T o
+@kindex T o (Summary)
+@findex gnus-summary-top-thread
+Go to the top of the thread (@code{gnus-summary-top-thread}).
+@end table
+
+@vindex gnus-thread-operation-ignore-subject
+If you ignore subject while threading, you'll naturally end up with
+threads that have several different subjects in them. If you then issue
+a command like @kbd{T k} (@code{gnus-summary-kill-thread}) you might not
+wish to kill the entire thread, but just those parts of the thread that
+have the same subject as the current article. If you like this idea,
+you can fiddle with @code{gnus-thread-operation-ignore-subject}. If it
+is non-@code{nil} (which it is by default), subjects will be ignored
+when doing thread commands. If this variable is @code{nil}, articles in
+the same thread with different subjects will not be included in the
+operation in question. If this variable is @code{fuzzy}, only articles
+that have subjects fuzzily equal will be included (@pxref{Fuzzy
+Matching}).
+
+
+@node Sorting the Summary Buffer
+@section Sorting the Summary Buffer
+
+@findex gnus-thread-sort-by-total-score
+@findex gnus-thread-sort-by-date
+@findex gnus-thread-sort-by-score
+@findex gnus-thread-sort-by-subject
+@findex gnus-thread-sort-by-author
+@findex gnus-thread-sort-by-recipient
+@findex gnus-thread-sort-by-number
+@findex gnus-thread-sort-by-random
+@vindex gnus-thread-sort-functions
+@findex gnus-thread-sort-by-most-recent-number
+@findex gnus-thread-sort-by-most-recent-date
+If you are using a threaded summary display, you can sort the threads by
+setting @code{gnus-thread-sort-functions}, which can be either a single
+function, a list of functions, or a list containing functions and
+@code{(not some-function)} elements.
+
+By default, sorting is done on article numbers. Ready-made sorting
+predicate functions include @code{gnus-thread-sort-by-number},
+@code{gnus-thread-sort-by-author}, @code{gnus-thread-sort-by-recipient},
+@code{gnus-thread-sort-by-subject},
+@code{gnus-thread-sort-by-date},
+@code{gnus-thread-sort-by-score},
+@code{gnus-thread-sort-by-most-recent-number},
+@code{gnus-thread-sort-by-most-recent-date},
+@code{gnus-thread-sort-by-random} and
+@code{gnus-thread-sort-by-total-score}.
+
+Each function takes two threads and returns non-@code{nil} if the first
+thread should be sorted before the other. Note that sorting really is
+normally done by looking only at the roots of each thread. Exceptions
+to this rule are @code{gnus-thread-sort-by-most-recent-number} and
+@code{gnus-thread-sort-by-most-recent-date}.
+
+If you use more than one function, the primary sort key should be the
+last function in the list. You should probably always include
+@code{gnus-thread-sort-by-number} in the list of sorting
+functions---preferably first. This will ensure that threads that are
+equal with respect to the other sort criteria will be displayed in
+ascending article order.
+
+If you would like to sort by reverse score, then by subject, and finally
+by number, you could do something like:
+
+@lisp
+(setq gnus-thread-sort-functions
+ '(gnus-thread-sort-by-number
+ gnus-thread-sort-by-subject
+ (not gnus-thread-sort-by-total-score)))
+@end lisp
+
+The threads that have highest score will be displayed first in the
+summary buffer. When threads have the same score, they will be sorted
+alphabetically. The threads that have the same score and the same
+subject will be sorted by number, which is (normally) the sequence in
+which the articles arrived.
+
+If you want to sort by score and then reverse arrival order, you could
+say something like:
+
+@lisp
+(setq gnus-thread-sort-functions
+ '((not gnus-thread-sort-by-number)
+ gnus-thread-sort-by-score))
+@end lisp
+
+By default, threads including their subthreads are sorted according to
+the value of @code{gnus-thread-sort-functions}. By customizing
+@code{gnus-subthread-sort-functions} you can define a custom sorting
+order for subthreads. This allows for example to sort threads from
+high score to low score in the summary buffer, but to have subthreads
+still sorted chronologically from old to new without taking their
+score into account.
+
+@vindex gnus-thread-score-function
+The function in the @code{gnus-thread-score-function} variable (default
+@code{+}) is used for calculating the total score of a thread. Useful
+functions might be @code{max}, @code{min}, or squared means, or whatever
+tickles your fancy.
+
+@findex gnus-article-sort-functions
+@findex gnus-article-sort-by-date
+@findex gnus-article-sort-by-most-recent-date
+@findex gnus-article-sort-by-score
+@findex gnus-article-sort-by-subject
+@findex gnus-article-sort-by-author
+@findex gnus-article-sort-by-random
+@findex gnus-article-sort-by-number
+@findex gnus-article-sort-by-most-recent-number
+If you are using an unthreaded display for some strange reason or
+other, you have to fiddle with the @code{gnus-article-sort-functions}
+variable. It is very similar to the
+@code{gnus-thread-sort-functions}, except that it uses slightly
+different functions for article comparison. Available sorting
+predicate functions are @code{gnus-article-sort-by-number},
+@code{gnus-article-sort-by-author},
+@code{gnus-article-sort-by-subject}, @code{gnus-article-sort-by-date},
+@code{gnus-article-sort-by-random}, and
+@code{gnus-article-sort-by-score}.
+
+If you want to sort an unthreaded summary display by subject, you could
+say something like:
+
+@lisp
+(setq gnus-article-sort-functions
+ '(gnus-article-sort-by-number
+ gnus-article-sort-by-subject))
+@end lisp
+
+You can define group specific sorting via @code{gnus-parameters},
+@xref{Group Parameters}.
+
+
+@node Asynchronous Fetching
+@section Asynchronous Article Fetching
+@cindex asynchronous article fetching
+@cindex article pre-fetch
+@cindex pre-fetch
+
+If you read your news from an @acronym{NNTP} server that's far away, the
+network latencies may make reading articles a chore. You have to wait
+for a while after pressing @kbd{n} to go to the next article before the
+article appears. Why can't Gnus just go ahead and fetch the article
+while you are reading the previous one? Why not, indeed.
+
+First, some caveats. There are some pitfalls to using asynchronous
+article fetching, especially the way Gnus does it.
+
+Let's say you are reading article 1, which is short, and article 2 is
+quite long, and you are not interested in reading that. Gnus does not
+know this, so it goes ahead and fetches article 2. You decide to read
+article 3, but since Gnus is in the process of fetching article 2, the
+connection is blocked.
+
+To avoid these situations, Gnus will open two (count 'em two)
+connections to the server. Some people may think this isn't a very nice
+thing to do, but I don't see any real alternatives. Setting up that
+extra connection takes some time, so Gnus startup will be slower.
+
+Gnus will fetch more articles than you will read. This will mean that
+the link between your machine and the @acronym{NNTP} server will become more
+loaded than if you didn't use article pre-fetch. The server itself will
+also become more loaded---both with the extra article requests, and the
+extra connection.
+
+Ok, so now you know that you shouldn't really use this thing@dots{} unless
+you really want to.
+
+@vindex gnus-asynchronous
+Here's how: Set @code{gnus-asynchronous} to @code{t}. The rest should
+happen automatically.
+
+@vindex gnus-use-article-prefetch
+You can control how many articles are to be pre-fetched by setting
+@code{gnus-use-article-prefetch}. This is 30 by default, which means
+that when you read an article in the group, the back end will pre-fetch
+the next 30 articles. If this variable is @code{t}, the back end will
+pre-fetch all the articles it can without bound. If it is
+@code{nil}, no pre-fetching will be done.
+
+@vindex gnus-async-prefetch-article-p
+@findex gnus-async-unread-p
+There are probably some articles that you don't want to pre-fetch---read
+articles, for instance. The @code{gnus-async-prefetch-article-p}
+variable controls whether an article is to be pre-fetched. This
+function should return non-@code{nil} when the article in question is
+to be pre-fetched. The default is @code{gnus-async-unread-p}, which
+returns @code{nil} on read articles. The function is called with an
+article data structure as the only parameter.
+
+If, for instance, you wish to pre-fetch only unread articles shorter
+than 100 lines, you could say something like:
+
+@lisp
+(defun my-async-short-unread-p (data)
+ "Return non-nil for short, unread articles."
+ (and (gnus-data-unread-p data)
+ (< (mail-header-lines (gnus-data-header data))
+ 100)))
+
+(setq gnus-async-prefetch-article-p 'my-async-short-unread-p)
+@end lisp
+
+These functions will be called many, many times, so they should
+preferably be short and sweet to avoid slowing down Gnus too much.
+It's probably a good idea to byte-compile things like this.
+
+@vindex gnus-async-post-fetch-function
+@findex gnus-html-prefetch-images
+After an article has been prefetched, this
+@code{gnus-async-post-fetch-function} will be called. The buffer will
+be narrowed to the region of the article that was fetched. A useful
+value would be @code{gnus-html-prefetch-images}, which will prefetch
+and store images referenced in the article, so that you don't have to
+wait for them to be fetched when you read the article. This is useful
+for @acronym{HTML} messages that have external images.
+
+@vindex gnus-prefetched-article-deletion-strategy
+Articles have to be removed from the asynch buffer sooner or later. The
+@code{gnus-prefetched-article-deletion-strategy} says when to remove
+articles. This is a list that may contain the following elements:
+
+@table @code
+@item read
+Remove articles when they are read.
+
+@item exit
+Remove articles when exiting the group.
+@end table
+
+The default value is @code{(read exit)}.
+
+@c @vindex gnus-use-header-prefetch
+@c If @code{gnus-use-header-prefetch} is non-@code{nil}, prefetch articles
+@c from the next group.
+
+
+@node Article Caching
+@section Article Caching
+@cindex article caching
+@cindex caching
+
+If you have an @emph{extremely} slow @acronym{NNTP} connection, you may
+consider turning article caching on. Each article will then be stored
+locally under your home directory. As you may surmise, this could
+potentially use @emph{huge} amounts of disk space, as well as eat up all
+your inodes so fast it will make your head swim. In vodka.
+
+Used carefully, though, it could be just an easier way to save articles.
+
+@vindex gnus-use-long-file-name
+@vindex gnus-cache-directory
+@vindex gnus-use-cache
+To turn caching on, set @code{gnus-use-cache} to @code{t}. By default,
+all articles ticked or marked as dormant will then be copied
+over to your local cache (@code{gnus-cache-directory}). Whether this
+cache is flat or hierarchical is controlled by the
+@code{gnus-use-long-file-name} variable, as usual.
+
+When re-selecting a ticked or dormant article, it will be fetched from the
+cache instead of from the server. As articles in your cache will never
+expire, this might serve as a method of saving articles while still
+keeping them where they belong. Just mark all articles you want to save
+as dormant, and don't worry.
+
+When an article is marked as read, is it removed from the cache.
+
+@vindex gnus-cache-remove-articles
+@vindex gnus-cache-enter-articles
+The entering/removal of articles from the cache is controlled by the
+@code{gnus-cache-enter-articles} and @code{gnus-cache-remove-articles}
+variables. Both are lists of symbols. The first is @code{(ticked
+dormant)} by default, meaning that ticked and dormant articles will be
+put in the cache. The latter is @code{(read)} by default, meaning that
+articles marked as read are removed from the cache. Possibly
+symbols in these two lists are @code{ticked}, @code{dormant},
+@code{unread} and @code{read}.
+
+@findex gnus-jog-cache
+So where does the massive article-fetching and storing come into the
+picture? The @code{gnus-jog-cache} command will go through all
+subscribed newsgroups, request all unread articles, score them, and
+store them in the cache. You should only ever, ever ever ever, use this
+command if 1) your connection to the @acronym{NNTP} server is really, really,
+really slow and 2) you have a really, really, really huge disk.
+Seriously. One way to cut down on the number of articles downloaded is
+to score unwanted articles down and have them marked as read. They will
+not then be downloaded by this command.
+
+@vindex gnus-uncacheable-groups
+@vindex gnus-cacheable-groups
+It is likely that you do not want caching on all groups. For instance,
+if your @code{nnml} mail is located under your home directory, it makes no
+sense to cache it somewhere else under your home directory. Unless you
+feel that it's neat to use twice as much space.
+
+To limit the caching, you could set @code{gnus-cacheable-groups} to a
+regexp of groups to cache, @samp{^nntp} for instance, or set the
+@code{gnus-uncacheable-groups} regexp to @samp{^nnml}, for instance.
+Both variables are @code{nil} by default. If a group matches both
+variables, the group is not cached.
+
+@findex gnus-cache-generate-nov-databases
+@findex gnus-cache-generate-active
+@vindex gnus-cache-active-file
+The cache stores information on what articles it contains in its active
+file (@code{gnus-cache-active-file}). If this file (or any other parts
+of the cache) becomes all messed up for some reason or other, Gnus
+offers two functions that will try to set things right. @kbd{M-x
+gnus-cache-generate-nov-databases} will (re)build all the @acronym{NOV}
+files, and @kbd{gnus-cache-generate-active} will (re)generate the active
+file.
+
+@findex gnus-cache-move-cache
+@code{gnus-cache-move-cache} will move your whole
+@code{gnus-cache-directory} to some other location. You get asked to
+where, isn't that cool?
+
+@node Persistent Articles
+@section Persistent Articles
+@cindex persistent articles
+
+Closely related to article caching, we have @dfn{persistent articles}.
+In fact, it's just a different way of looking at caching, and much more
+useful in my opinion.
+
+Say you're reading a newsgroup, and you happen on to some valuable gem
+that you want to keep and treasure forever. You'd normally just save it
+(using one of the many saving commands) in some file. The problem with
+that is that it's just, well, yucky. Ideally you'd prefer just having
+the article remain in the group where you found it forever; untouched by
+the expiry going on at the news server.
+
+This is what a @dfn{persistent article} is---an article that just won't
+be deleted. It's implemented using the normal cache functions, but
+you use two explicit commands for managing persistent articles:
+
+@table @kbd
+
+@item *
+@kindex * (Summary)
+@findex gnus-cache-enter-article
+Make the current article persistent (@code{gnus-cache-enter-article}).
+
+@item M-*
+@kindex M-* (Summary)
+@findex gnus-cache-remove-article
+Remove the current article from the persistent articles
+(@code{gnus-cache-remove-article}). This will normally delete the
+article.
+@end table
+
+Both these commands understand the process/prefix convention.
+
+To avoid having all ticked articles (and stuff) entered into the cache,
+you should set @code{gnus-use-cache} to @code{passive} if you're just
+interested in persistent articles:
+
+@lisp
+(setq gnus-use-cache 'passive)
+@end lisp
+
+@node Sticky Articles
+@section Sticky Articles
+@cindex sticky articles
+
+When you select an article the current article buffer will be reused
+according to the value of the variable
+@code{gnus-single-article-buffer}. If its value is non-@code{nil} (the
+default) all articles reuse the same article buffer. Else each group
+has its own article buffer.
+
+This implies that it's not possible to have more than one article buffer
+in a group at a time. But sometimes you might want to display all the
+latest emails from your mother, your father, your aunt, your uncle and
+your 17 cousins to coordinate the next Christmas party.
+
+That's where sticky articles come in handy. A sticky article buffer
+basically is a normal article buffer, but it won't be reused when you
+select another article. You can make an article sticky with:
+
+@table @kbd
+@item A S
+@kindex A S (Summary)
+@findex gnus-sticky-article
+Make the current article sticky. If a prefix arg is given, ask for a
+name for this sticky article buffer.
+@end table
+
+To close a sticky article buffer you can use these commands:
+
+@table @kbd
+@item q
+@kindex q (Article)
+@findex bury-buffer
+Puts this sticky article buffer at the end of the list of all buffers.
+
+@item k
+@kindex k (Article)
+@findex gnus-kill-sticky-article-buffer
+Kills this sticky article buffer.
+@end table
+
+To kill all sticky article buffers you can use:
+
+@defun gnus-kill-sticky-article-buffers ARG
+Kill all sticky article buffers.
+If a prefix ARG is given, ask for confirmation.
+@end defun
+
+@node Article Backlog
+@section Article Backlog
+@cindex backlog
+@cindex article backlog
+
+If you have a slow connection, but the idea of using caching seems
+unappealing to you (and it is, really), you can help the situation some
+by switching on the @dfn{backlog}. This is where Gnus will buffer
+already read articles so that it doesn't have to re-fetch articles
+you've already read. This only helps if you are in the habit of
+re-selecting articles you've recently read, of course. If you never do
+that, turning the backlog on will slow Gnus down a little bit, and
+increase memory usage some.
+
+@vindex gnus-keep-backlog
+If you set @code{gnus-keep-backlog} to a number @var{n}, Gnus will store
+at most @var{n} old articles in a buffer for later re-fetching. If this
+variable is non-@code{nil} and is not a number, Gnus will store
+@emph{all} read articles, which means that your Emacs will grow without
+bound before exploding and taking your machine down with you. I put
+that in there just to keep y'all on your toes.
+
+The default value is 20.
+
+
+@node Saving Articles
+@section Saving Articles
+@cindex saving articles
+
+Gnus can save articles in a number of ways. Below is the documentation
+for saving articles in a fairly straight-forward fashion (i.e., little
+processing of the article is done before it is saved). For a different
+approach (uudecoding, unsharing) you should use @code{gnus-uu}
+(@pxref{Decoding Articles}).
+
+For the commands listed here, the target is a file. If you want to
+save to a group, see the @kbd{B c} (@code{gnus-summary-copy-article})
+command (@pxref{Mail Group Commands}).
+
+@vindex gnus-save-all-headers
+If @code{gnus-save-all-headers} is non-@code{nil}, Gnus will not delete
+unwanted headers before saving the article.
+
+@vindex gnus-saved-headers
+If the preceding variable is @code{nil}, all headers that match the
+@code{gnus-saved-headers} regexp will be kept, while the rest will be
+deleted before saving.
+
+@table @kbd
+
+@item O o
+@itemx o
+@kindex O o (Summary)
+@kindex o (Summary)
+@findex gnus-summary-save-article
+@c @icon{gnus-summary-save-article}
+Save the current article using the default article saver
+(@code{gnus-summary-save-article}).
+
+@item O m
+@kindex O m (Summary)
+@findex gnus-summary-save-article-mail
+Save the current article in a Unix mail box (mbox) file
+(@code{gnus-summary-save-article-mail}).
+
+@item O r
+@kindex O r (Summary)
+@findex gnus-summary-save-article-rmail
+Save the current article in Rmail format
+(@code{gnus-summary-save-article-rmail}). This is mbox since Emacs 23,
+Babyl in older versions.
+
+@item O f
+@kindex O f (Summary)
+@findex gnus-summary-save-article-file
+@c @icon{gnus-summary-save-article-file}
+Save the current article in plain file format
+(@code{gnus-summary-save-article-file}).
+
+@item O F
+@kindex O F (Summary)
+@findex gnus-summary-write-article-file
+Write the current article in plain file format, overwriting any previous
+file contents (@code{gnus-summary-write-article-file}).
+
+@item O b
+@kindex O b (Summary)
+@findex gnus-summary-save-article-body-file
+Save the current article body in plain file format
+(@code{gnus-summary-save-article-body-file}).
+
+@item O h
+@kindex O h (Summary)
+@findex gnus-summary-save-article-folder
+Save the current article in mh folder format
+(@code{gnus-summary-save-article-folder}).
+
+@item O v
+@kindex O v (Summary)
+@findex gnus-summary-save-article-vm
+Save the current article in a VM folder
+(@code{gnus-summary-save-article-vm}).
+
+@item O p
+@itemx |
+@kindex O p (Summary)
+@kindex | (Summary)
+@findex gnus-summary-pipe-output
+@vindex gnus-summary-pipe-output-default-command
+Save the current article in a pipe. Uhm, like, what I mean is---Pipe
+the current article to a process (@code{gnus-summary-pipe-output}).
+If given a symbolic prefix (@pxref{Symbolic Prefixes}), include the
+complete headers in the piped output. The symbolic prefix @code{r} is
+special; it lets this command pipe a raw article including all headers.
+The @code{gnus-summary-pipe-output-default-command} variable can be set
+to a string containing the default command and options (default
+@code{nil}).
+
+@item O P
+@kindex O P (Summary)
+@findex gnus-summary-muttprint
+@vindex gnus-summary-muttprint-program
+Save the current article into muttprint. That is, print it using the
+external program @uref{http://muttprint.sourceforge.net/,
+Muttprint}. The program name and options to use is controlled by the
+variable @code{gnus-summary-muttprint-program}.
+(@code{gnus-summary-muttprint}).
+
+@end table
+
+@vindex gnus-prompt-before-saving
+All these commands use the process/prefix convention
+(@pxref{Process/Prefix}). If you save bunches of articles using these
+functions, you might get tired of being prompted for files to save each
+and every article in. The prompting action is controlled by
+the @code{gnus-prompt-before-saving} variable, which is @code{always} by
+default, giving you that excessive prompting action you know and
+loathe. If you set this variable to @code{t} instead, you'll be prompted
+just once for each series of articles you save. If you like to really
+have Gnus do all your thinking for you, you can even set this variable
+to @code{nil}, which means that you will never be prompted for files to
+save articles in. Gnus will simply save all the articles in the default
+files.
+
+
+@vindex gnus-default-article-saver
+You can customize the @code{gnus-default-article-saver} variable to make
+Gnus do what you want it to. You can use any of the eight ready-made
+functions below, or you can create your own.
+
+@table @code
+
+@item gnus-summary-save-in-rmail
+@findex gnus-summary-save-in-rmail
+@vindex gnus-rmail-save-name
+@findex gnus-plain-save-name
+This is the default format, that used by the Rmail package. Since Emacs
+23, Rmail uses standard mbox format. Before this, it used the
+@dfn{Babyl} format. Accordingly, this command writes mbox format since
+Emacs 23, unless appending to an existing Babyl file. In older versions
+of Emacs, it always uses Babyl format. Uses the function in the
+@code{gnus-rmail-save-name} variable to get a file name to save the
+article in. The default is @code{gnus-plain-save-name}.
+
+@item gnus-summary-save-in-mail
+@findex gnus-summary-save-in-mail
+@vindex gnus-mail-save-name
+Save in a Unix mail (mbox) file. Uses the function in the
+@code{gnus-mail-save-name} variable to get a file name to save the
+article in. The default is @code{gnus-plain-save-name}.
+
+@item gnus-summary-save-in-file
+@findex gnus-summary-save-in-file
+@vindex gnus-file-save-name
+@findex gnus-numeric-save-name
+Append the article straight to an ordinary file. Uses the function in
+the @code{gnus-file-save-name} variable to get a file name to save the
+article in. The default is @code{gnus-numeric-save-name}.
+
+@item gnus-summary-write-to-file
+@findex gnus-summary-write-to-file
+Write the article straight to an ordinary file. The file is
+overwritten if it exists. Uses the function in the
+@code{gnus-file-save-name} variable to get a file name to save the
+article in. The default is @code{gnus-numeric-save-name}.
+
+@item gnus-summary-save-body-in-file
+@findex gnus-summary-save-body-in-file
+Append the article body to an ordinary file. Uses the function in the
+@code{gnus-file-save-name} variable to get a file name to save the
+article in. The default is @code{gnus-numeric-save-name}.
+
+@item gnus-summary-write-body-to-file
+@findex gnus-summary-write-body-to-file
+Write the article body straight to an ordinary file. The file is
+overwritten if it exists. Uses the function in the
+@code{gnus-file-save-name} variable to get a file name to save the
+article in. The default is @code{gnus-numeric-save-name}.
+
+@item gnus-summary-save-in-folder
+@findex gnus-summary-save-in-folder
+@findex gnus-folder-save-name
+@findex gnus-Folder-save-name
+@vindex gnus-folder-save-name
+@cindex rcvstore
+@cindex MH folders
+Save the article to an MH folder using @code{rcvstore} from the MH
+library. Uses the function in the @code{gnus-folder-save-name} variable
+to get a file name to save the article in. The default is
+@code{gnus-folder-save-name}, but you can also use
+@code{gnus-Folder-save-name}, which creates capitalized names.
+
+@item gnus-summary-save-in-vm
+@findex gnus-summary-save-in-vm
+Save the article in a VM folder. You have to have the VM mail
+reader to use this setting.
+
+@item gnus-summary-save-in-pipe
+@findex gnus-summary-save-in-pipe
+Pipe the article to a shell command. This function takes optional two
+arguments COMMAND and RAW@. Valid values for COMMAND include:
+
+@itemize @bullet
+@item a string@*
+The executable command name and possibly arguments.
+@item @code{nil}@*
+You will be prompted for the command in the minibuffer.
+@item the symbol @code{default}@*
+It will be replaced with the command which the variable
+@code{gnus-summary-pipe-output-default-command} holds or the command
+last used for saving.
+@end itemize
+
+Non-@code{nil} value for RAW overrides @code{:decode} and
+@code{:headers} properties (see below) and the raw article including all
+headers will be piped.
+@end table
+
+The symbol of each function may have the following properties:
+
+@table @code
+@item :decode
+The value non-@code{nil} means save decoded articles. This is
+meaningful only with @code{gnus-summary-save-in-file},
+@code{gnus-summary-save-body-in-file},
+@code{gnus-summary-write-to-file},
+@code{gnus-summary-write-body-to-file}, and
+@code{gnus-summary-save-in-pipe}.
+
+@item :function
+The value specifies an alternative function which appends, not
+overwrites, articles to a file. This implies that when saving many
+articles at a time, @code{gnus-prompt-before-saving} is bound to
+@code{t} and all articles are saved in a single file. This is
+meaningful only with @code{gnus-summary-write-to-file} and
+@code{gnus-summary-write-body-to-file}.
+
+@item :headers
+The value specifies the symbol of a variable of which the value
+specifies headers to be saved. If it is omitted,
+@code{gnus-save-all-headers} and @code{gnus-saved-headers} control what
+headers should be saved.
+@end table
+
+@vindex gnus-article-save-directory
+All of these functions, except for the last one, will save the article
+in the @code{gnus-article-save-directory}, which is initialized from the
+@env{SAVEDIR} environment variable. This is @file{~/News/} by
+default.
+
+As you can see above, the functions use different functions to find a
+suitable name of a file to save the article in. Below is a list of
+available functions that generate names:
+
+@table @code
+
+@item gnus-Numeric-save-name
+@findex gnus-Numeric-save-name
+File names like @file{~/News/Alt.andrea-dworkin/45}.
+
+@item gnus-numeric-save-name
+@findex gnus-numeric-save-name
+File names like @file{~/News/alt.andrea-dworkin/45}.
+
+@item gnus-Plain-save-name
+@findex gnus-Plain-save-name
+File names like @file{~/News/Alt.andrea-dworkin}.
+
+@item gnus-plain-save-name
+@findex gnus-plain-save-name
+File names like @file{~/News/alt.andrea-dworkin}.
+
+@item gnus-sender-save-name
+@findex gnus-sender-save-name
+File names like @file{~/News/larsi}.
+@end table
+
+@vindex gnus-split-methods
+You can have Gnus suggest where to save articles by plonking a regexp into
+the @code{gnus-split-methods} alist. For instance, if you would like to
+save articles related to Gnus in the file @file{gnus-stuff}, and articles
+related to VM in @file{vm-stuff}, you could set this variable to something
+like:
+
+@lisp
+(("^Subject:.*gnus\\|^Newsgroups:.*gnus" "gnus-stuff")
+ ("^Subject:.*vm\\|^Xref:.*vm" "vm-stuff")
+ (my-choosing-function "../other-dir/my-stuff")
+ ((equal gnus-newsgroup-name "mail.misc") "mail-stuff"))
+@end lisp
+
+We see that this is a list where each element is a list that has two
+elements---the @dfn{match} and the @dfn{file}. The match can either be
+a string (in which case it is used as a regexp to match on the article
+head); it can be a symbol (which will be called as a function with the
+group name as a parameter); or it can be a list (which will be
+@code{eval}ed). If any of these actions have a non-@code{nil} result,
+the @dfn{file} will be used as a default prompt. In addition, the
+result of the operation itself will be used if the function or form
+called returns a string or a list of strings.
+
+You basically end up with a list of file names that might be used when
+saving the current article. (All ``matches'' will be used.) You will
+then be prompted for what you really want to use as a name, with file
+name completion over the results from applying this variable.
+
+This variable is @code{((gnus-article-archive-name))} by default, which
+means that Gnus will look at the articles it saves for an
+@code{Archive-name} line and use that as a suggestion for the file
+name.
+
+Here's an example function to clean up file names somewhat. If you have
+lots of mail groups called things like
+@samp{nnml:mail.whatever}, you may want to chop off the beginning of
+these group names before creating the file name to save to. The
+following will do just that:
+
+@lisp
+(defun my-save-name (group)
+ (when (string-match "^nnml:mail." group)
+ (substring group (match-end 0))))
+
+(setq gnus-split-methods
+ '((gnus-article-archive-name)
+ (my-save-name)))
+@end lisp
+
+
+@vindex gnus-use-long-file-name
+Finally, you have the @code{gnus-use-long-file-name} variable. If it is
+@code{nil}, all the preceding functions will replace all periods
+(@samp{.}) in the group names with slashes (@samp{/})---which means that
+the functions will generate hierarchies of directories instead of having
+all the files in the top level directory
+(@file{~/News/alt/andrea-dworkin} instead of
+@file{~/News/alt.andrea-dworkin}.) This variable is @code{t} by default
+on most systems. However, for historical reasons, this is @code{nil} on
+Xenix and usg-unix-v machines by default.
+
+This function also affects kill and score file names. If this variable
+is a list, and the list contains the element @code{not-score}, long file
+names will not be used for score files, if it contains the element
+@code{not-save}, long file names will not be used for saving, and if it
+contains the element @code{not-kill}, long file names will not be used
+for kill files.
+
+If you'd like to save articles in a hierarchy that looks something like
+a spool, you could
+
+@lisp
+(setq gnus-use-long-file-name '(not-save)) ; @r{to get a hierarchy}
+(setq gnus-default-article-saver
+ 'gnus-summary-save-in-file) ; @r{no encoding}
+@end lisp
+
+Then just save with @kbd{o}. You'd then read this hierarchy with
+ephemeral @code{nneething} groups---@kbd{G D} in the group buffer, and
+the top level directory as the argument (@file{~/News/}). Then just walk
+around to the groups/directories with @code{nneething}.
+
+
+@node Decoding Articles
+@section Decoding Articles
+@cindex decoding articles
+
+Sometime users post articles (or series of articles) that have been
+encoded in some way or other. Gnus can decode them for you.
+
+@menu
+* Uuencoded Articles:: Uudecode articles.
+* Shell Archives:: Unshar articles.
+* PostScript Files:: Split PostScript.
+* Other Files:: Plain save and binhex.
+* Decoding Variables:: Variables for a happy decoding.
+* Viewing Files:: You want to look at the result of the decoding?
+@end menu
+
+@cindex series
+@cindex article series
+All these functions use the process/prefix convention
+(@pxref{Process/Prefix}) for finding out what articles to work on, with
+the extension that a ``single article'' means ``a single series''. Gnus
+can find out by itself what articles belong to a series, decode all the
+articles and unpack/view/save the resulting file(s).
+
+Gnus guesses what articles are in the series according to the following
+simplish rule: The subjects must be (nearly) identical, except for the
+last two numbers of the line. (Spaces are largely ignored, however.)
+
+For example: If you choose a subject called @samp{cat.gif (2/3)}, Gnus
+will find all the articles that match the regexp @samp{^cat.gif
+([0-9]+/[0-9]+).*$}.
+
+Subjects that are non-standard, like @samp{cat.gif (2/3) Part 6 of a
+series}, will not be properly recognized by any of the automatic viewing
+commands, and you have to mark the articles manually with @kbd{#}.
+
+
+@node Uuencoded Articles
+@subsection Uuencoded Articles
+@cindex uudecode
+@cindex uuencoded articles
+
+@table @kbd
+
+@item X u
+@kindex X u (Summary)
+@findex gnus-uu-decode-uu
+@c @icon{gnus-uu-decode-uu}
+Uudecodes the current series (@code{gnus-uu-decode-uu}).
+
+@item X U
+@kindex X U (Summary)
+@findex gnus-uu-decode-uu-and-save
+Uudecodes and saves the current series
+(@code{gnus-uu-decode-uu-and-save}).
+
+@item X v u
+@kindex X v u (Summary)
+@findex gnus-uu-decode-uu-view
+Uudecodes and views the current series (@code{gnus-uu-decode-uu-view}).
+
+@item X v U
+@kindex X v U (Summary)
+@findex gnus-uu-decode-uu-and-save-view
+Uudecodes, views and saves the current series
+(@code{gnus-uu-decode-uu-and-save-view}).
+
+@end table
+
+Remember that these all react to the presence of articles marked with
+the process mark. If, for instance, you'd like to decode and save an
+entire newsgroup, you'd typically do @kbd{M P a}
+(@code{gnus-uu-mark-all}) and then @kbd{X U}
+(@code{gnus-uu-decode-uu-and-save}).
+
+All this is very much different from how @code{gnus-uu} worked with
+@sc{gnus 4.1}, where you had explicit keystrokes for everything under
+the sun. This version of @code{gnus-uu} generally assumes that you mark
+articles in some way (@pxref{Setting Process Marks}) and then press
+@kbd{X u}.
+
+@vindex gnus-uu-notify-files
+Note: When trying to decode articles that have names matching
+@code{gnus-uu-notify-files}, which is hard-coded to
+@samp{[Cc][Ii][Nn][Dd][Yy][0-9]+.\\(gif\\|jpg\\)}, @code{gnus-uu} will
+automatically post an article on @samp{comp.unix.wizards} saying that
+you have just viewed the file in question. This feature can't be turned
+off.
+
+
+@node Shell Archives
+@subsection Shell Archives
+@cindex unshar
+@cindex shell archives
+@cindex shared articles
+
+Shell archives (``shar files'') used to be a popular way to distribute
+sources, but it isn't used all that much today. In any case, we have
+some commands to deal with these:
+
+@table @kbd
+
+@item X s
+@kindex X s (Summary)
+@findex gnus-uu-decode-unshar
+Unshars the current series (@code{gnus-uu-decode-unshar}).
+
+@item X S
+@kindex X S (Summary)
+@findex gnus-uu-decode-unshar-and-save
+Unshars and saves the current series (@code{gnus-uu-decode-unshar-and-save}).
+
+@item X v s
+@kindex X v s (Summary)
+@findex gnus-uu-decode-unshar-view
+Unshars and views the current series (@code{gnus-uu-decode-unshar-view}).
+
+@item X v S
+@kindex X v S (Summary)
+@findex gnus-uu-decode-unshar-and-save-view
+Unshars, views and saves the current series
+(@code{gnus-uu-decode-unshar-and-save-view}).
+@end table
+
+
+@node PostScript Files
+@subsection PostScript Files
+@cindex PostScript
+
+@table @kbd
+
+@item X p
+@kindex X p (Summary)
+@findex gnus-uu-decode-postscript
+Unpack the current PostScript series (@code{gnus-uu-decode-postscript}).
+
+@item X P
+@kindex X P (Summary)
+@findex gnus-uu-decode-postscript-and-save
+Unpack and save the current PostScript series
+(@code{gnus-uu-decode-postscript-and-save}).
+
+@item X v p
+@kindex X v p (Summary)
+@findex gnus-uu-decode-postscript-view
+View the current PostScript series
+(@code{gnus-uu-decode-postscript-view}).
+
+@item X v P
+@kindex X v P (Summary)
+@findex gnus-uu-decode-postscript-and-save-view
+View and save the current PostScript series
+(@code{gnus-uu-decode-postscript-and-save-view}).
+@end table
+
+
+@node Other Files
+@subsection Other Files
+
+@table @kbd
+@item X o
+@kindex X o (Summary)
+@findex gnus-uu-decode-save
+Save the current series
+(@code{gnus-uu-decode-save}).
+
+@item X b
+@kindex X b (Summary)
+@findex gnus-uu-decode-binhex
+Unbinhex the current series (@code{gnus-uu-decode-binhex}). This
+doesn't really work yet.
+
+@item X Y
+@kindex X Y (Summary)
+@findex gnus-uu-decode-yenc
+yEnc-decode the current series and save it (@code{gnus-uu-decode-yenc}).
+@end table
+
+
+@node Decoding Variables
+@subsection Decoding Variables
+
+Adjective, not verb.
+
+@menu
+* Rule Variables:: Variables that say how a file is to be viewed.
+* Other Decode Variables:: Other decode variables.
+* Uuencoding and Posting:: Variables for customizing uuencoding.
+@end menu
+
+
+@node Rule Variables
+@subsubsection Rule Variables
+@cindex rule variables
+
+Gnus uses @dfn{rule variables} to decide how to view a file. All these
+variables are of the form
+
+@lisp
+ (list '(regexp1 command2)
+ '(regexp2 command2)
+ ...)
+@end lisp
+
+@table @code
+
+@item gnus-uu-user-view-rules
+@vindex gnus-uu-user-view-rules
+@cindex sox
+This variable is consulted first when viewing files. If you wish to use,
+for instance, @code{sox} to convert an @file{.au} sound file, you could
+say something like:
+@lisp
+(setq gnus-uu-user-view-rules
+ (list '("\\\\.au$" "sox %s -t .aiff > /dev/audio")))
+@end lisp
+
+@item gnus-uu-user-view-rules-end
+@vindex gnus-uu-user-view-rules-end
+This variable is consulted if Gnus couldn't make any matches from the
+user and default view rules.
+
+@item gnus-uu-user-archive-rules
+@vindex gnus-uu-user-archive-rules
+This variable can be used to say what commands should be used to unpack
+archives.
+@end table
+
+
+@node Other Decode Variables
+@subsubsection Other Decode Variables
+
+@table @code
+@vindex gnus-uu-grabbed-file-functions
+
+@item gnus-uu-grabbed-file-functions
+All functions in this list will be called right after each file has been
+successfully decoded---so that you can move or view files right away,
+and don't have to wait for all files to be decoded before you can do
+anything. Ready-made functions you can put in this list are:
+
+@table @code
+
+@item gnus-uu-grab-view
+@findex gnus-uu-grab-view
+View the file.
+
+@item gnus-uu-grab-move
+@findex gnus-uu-grab-move
+Move the file (if you're using a saving function.)
+@end table
+
+@item gnus-uu-be-dangerous
+@vindex gnus-uu-be-dangerous
+Specifies what to do if unusual situations arise during decoding. If
+@code{nil}, be as conservative as possible. If @code{t}, ignore things
+that didn't work, and overwrite existing files. Otherwise, ask each
+time.
+
+@item gnus-uu-ignore-files-by-name
+@vindex gnus-uu-ignore-files-by-name
+Files with name matching this regular expression won't be viewed.
+
+@item gnus-uu-ignore-files-by-type
+@vindex gnus-uu-ignore-files-by-type
+Files with a @acronym{MIME} type matching this variable won't be viewed.
+Note that Gnus tries to guess what type the file is based on the name.
+@code{gnus-uu} is not a @acronym{MIME} package (yet), so this is slightly
+kludgy.
+
+@item gnus-uu-tmp-dir
+@vindex gnus-uu-tmp-dir
+Where @code{gnus-uu} does its work.
+
+@item gnus-uu-do-not-unpack-archives
+@vindex gnus-uu-do-not-unpack-archives
+Non-@code{nil} means that @code{gnus-uu} won't peek inside archives
+looking for files to display.
+
+@item gnus-uu-view-and-save
+@vindex gnus-uu-view-and-save
+Non-@code{nil} means that the user will always be asked to save a file
+after viewing it.
+
+@item gnus-uu-ignore-default-view-rules
+@vindex gnus-uu-ignore-default-view-rules
+Non-@code{nil} means that @code{gnus-uu} will ignore the default viewing
+rules.
+
+@item gnus-uu-ignore-default-archive-rules
+@vindex gnus-uu-ignore-default-archive-rules
+Non-@code{nil} means that @code{gnus-uu} will ignore the default archive
+unpacking commands.
+
+@item gnus-uu-kill-carriage-return
+@vindex gnus-uu-kill-carriage-return
+Non-@code{nil} means that @code{gnus-uu} will strip all carriage returns
+from articles.
+
+@item gnus-uu-unmark-articles-not-decoded
+@vindex gnus-uu-unmark-articles-not-decoded
+Non-@code{nil} means that @code{gnus-uu} will mark unsuccessfully
+decoded articles as unread.
+
+@item gnus-uu-correct-stripped-uucode
+@vindex gnus-uu-correct-stripped-uucode
+Non-@code{nil} means that @code{gnus-uu} will @emph{try} to fix
+uuencoded files that have had trailing spaces deleted.
+
+@item gnus-uu-pre-uudecode-hook
+@vindex gnus-uu-pre-uudecode-hook
+Hook run before sending a message to @code{uudecode}.
+
+@item gnus-uu-view-with-metamail
+@vindex gnus-uu-view-with-metamail
+@cindex metamail
+Non-@code{nil} means that @code{gnus-uu} will ignore the viewing
+commands defined by the rule variables and just fudge a @acronym{MIME}
+content type based on the file name. The result will be fed to
+@code{metamail} for viewing.
+
+@item gnus-uu-save-in-digest
+@vindex gnus-uu-save-in-digest
+Non-@code{nil} means that @code{gnus-uu}, when asked to save without
+decoding, will save in digests. If this variable is @code{nil},
+@code{gnus-uu} will just save everything in a file without any
+embellishments. The digesting almost conforms to RFC 1153---no easy way
+to specify any meaningful volume and issue numbers were found, so I
+simply dropped them.
+
+@end table
+
+
+@node Uuencoding and Posting
+@subsubsection Uuencoding and Posting
+
+@table @code
+
+@item gnus-uu-post-include-before-composing
+@vindex gnus-uu-post-include-before-composing
+Non-@code{nil} means that @code{gnus-uu} will ask for a file to encode
+before you compose the article. If this variable is @code{t}, you can
+either include an encoded file with @kbd{C-c C-i} or have one included
+for you when you post the article.
+
+@item gnus-uu-post-length
+@vindex gnus-uu-post-length
+Maximum length of an article. The encoded file will be split into how
+many articles it takes to post the entire file.
+
+@item gnus-uu-post-threaded
+@vindex gnus-uu-post-threaded
+Non-@code{nil} means that @code{gnus-uu} will post the encoded file in a
+thread. This may not be smart, as no other decoder I have seen is able
+to follow threads when collecting uuencoded articles. (Well, I have
+seen one package that does that---@code{gnus-uu}, but somehow, I don't
+think that counts@dots{}) Default is @code{nil}.
+
+@item gnus-uu-post-separate-description
+@vindex gnus-uu-post-separate-description
+Non-@code{nil} means that the description will be posted in a separate
+article. The first article will typically be numbered (0/x). If this
+variable is @code{nil}, the description the user enters will be included
+at the beginning of the first article, which will be numbered (1/x).
+Default is @code{t}.
+
+@end table
+
+
+@node Viewing Files
+@subsection Viewing Files
+@cindex viewing files
+@cindex pseudo-articles
+
+After decoding, if the file is some sort of archive, Gnus will attempt
+to unpack the archive and see if any of the files in the archive can be
+viewed. For instance, if you have a gzipped tar file @file{pics.tar.gz}
+containing the files @file{pic1.jpg} and @file{pic2.gif}, Gnus will
+uncompress and de-tar the main file, and then view the two pictures.
+This unpacking process is recursive, so if the archive contains archives
+of archives, it'll all be unpacked.
+
+Finally, Gnus will normally insert a @dfn{pseudo-article} for each
+extracted file into the summary buffer. If you go to these
+``articles'', you will be prompted for a command to run (usually Gnus
+will make a suggestion), and then the command will be run.
+
+@vindex gnus-view-pseudo-asynchronously
+If @code{gnus-view-pseudo-asynchronously} is @code{nil}, Emacs will wait
+until the viewing is done before proceeding.
+
+@vindex gnus-view-pseudos
+If @code{gnus-view-pseudos} is @code{automatic}, Gnus will not insert
+the pseudo-articles into the summary buffer, but view them
+immediately. If this variable is @code{not-confirm}, the user won't even
+be asked for a confirmation before viewing is done.
+
+@vindex gnus-view-pseudos-separately
+If @code{gnus-view-pseudos-separately} is non-@code{nil}, one
+pseudo-article will be created for each file to be viewed. If
+@code{nil}, all files that use the same viewing command will be given as
+a list of parameters to that command.
+
+@vindex gnus-insert-pseudo-articles
+If @code{gnus-insert-pseudo-articles} is non-@code{nil}, insert
+pseudo-articles when decoding. It is @code{t} by default.
+
+So; there you are, reading your @emph{pseudo-articles} in your
+@emph{virtual newsgroup} from the @emph{virtual server}; and you think:
+Why isn't anything real anymore? How did we get here?
+
+
+@node Article Treatment
+@section Article Treatment
+
+Reading through this huge manual, you may have quite forgotten that the
+object of newsreaders is to actually, like, read what people have
+written. Reading articles. Unfortunately, people are quite bad at
+writing, so there are tons of functions and variables to make reading
+these articles easier.
+
+@menu
+* Article Highlighting:: You want to make the article look like fruit salad.
+* Article Fontisizing:: Making emphasized text look nice.
+* Article Hiding:: You also want to make certain info go away.
+* Article Washing:: Lots of way-neat functions to make life better.
+* Article Header:: Doing various header transformations.
+* Article Buttons:: Click on URLs, Message-IDs, addresses and the like.
+* Article Button Levels:: Controlling appearance of buttons.
+* Article Date:: Grumble, UT!
+* Article Display:: Display various stuff:
+ X-Face, Picons, Gravatars, Smileys.
+* Article Signature:: What is a signature?
+* Article Miscellanea:: Various other stuff.
+@end menu
+
+
+@node Article Highlighting
+@subsection Article Highlighting
+@cindex highlighting
+
+Not only do you want your article buffer to look like fruit salad, but
+you want it to look like technicolor fruit salad.
+
+@table @kbd
+
+@item W H a
+@kindex W H a (Summary)
+@findex gnus-article-highlight
+@findex gnus-article-maybe-highlight
+Do much highlighting of the current article
+(@code{gnus-article-highlight}). This function highlights header, cited
+text, the signature, and adds buttons to the body and the head.
+
+@item W H h
+@kindex W H h (Summary)
+@findex gnus-article-highlight-headers
+@vindex gnus-header-face-alist
+Highlight the headers (@code{gnus-article-highlight-headers}). The
+highlighting will be done according to the @code{gnus-header-face-alist}
+variable, which is a list where each element has the form
+@code{(@var{regexp} @var{name} @var{content})}.
+@var{regexp} is a regular expression for matching the
+header, @var{name} is the face used for highlighting the header name
+(@pxref{Faces and Fonts}) and @var{content} is the face for highlighting
+the header value. The first match made will be used. Note that
+@var{regexp} shouldn't have @samp{^} prepended---Gnus will add one.
+
+@item W H c
+@kindex W H c (Summary)
+@findex gnus-article-highlight-citation
+Highlight cited text (@code{gnus-article-highlight-citation}).
+
+Some variables to customize the citation highlights:
+
+@table @code
+@vindex gnus-cite-parse-max-size
+
+@item gnus-cite-parse-max-size
+If the article size in bytes is bigger than this variable (which is
+25000 by default), no citation highlighting will be performed.
+
+@item gnus-cite-max-prefix
+@vindex gnus-cite-max-prefix
+Maximum possible length for a citation prefix (default 20).
+
+@item gnus-cite-face-list
+@vindex gnus-cite-face-list
+List of faces used for highlighting citations (@pxref{Faces and Fonts}).
+When there are citations from multiple articles in the same message,
+Gnus will try to give each citation from each article its own face.
+This should make it easier to see who wrote what.
+
+@item gnus-supercite-regexp
+@vindex gnus-supercite-regexp
+Regexp matching normal Supercite attribution lines.
+
+@item gnus-supercite-secondary-regexp
+@vindex gnus-supercite-secondary-regexp
+Regexp matching mangled Supercite attribution lines.
+
+@item gnus-cite-minimum-match-count
+@vindex gnus-cite-minimum-match-count
+Minimum number of identical prefixes we have to see before we believe
+that it's a citation.
+
+@item gnus-cite-attribution-prefix
+@vindex gnus-cite-attribution-prefix
+Regexp matching the beginning of an attribution line.
+
+@item gnus-cite-attribution-suffix
+@vindex gnus-cite-attribution-suffix
+Regexp matching the end of an attribution line.
+
+@item gnus-cite-attribution-face
+@vindex gnus-cite-attribution-face
+Face used for attribution lines. It is merged with the face for the
+cited text belonging to the attribution.
+
+@item gnus-cite-ignore-quoted-from
+@vindex gnus-cite-ignore-quoted-from
+If non-@code{nil}, no citation highlighting will be performed on lines
+beginning with @samp{>From }. Those lines may have been quoted by MTAs
+in order not to mix up with the envelope From line. The default value
+is @code{t}.
+
+@end table
+
+
+@item W H s
+@kindex W H s (Summary)
+@vindex gnus-signature-separator
+@vindex gnus-signature-face
+@findex gnus-article-highlight-signature
+Highlight the signature (@code{gnus-article-highlight-signature}).
+Everything after @code{gnus-signature-separator} (@pxref{Article
+Signature}) in an article will be considered a signature and will be
+highlighted with @code{gnus-signature-face}, which is @code{italic} by
+default.
+
+@end table
+
+@xref{Customizing Articles}, for how to highlight articles automatically.
+
+
+@node Article Fontisizing
+@subsection Article Fontisizing
+@cindex emphasis
+@cindex article emphasis
+
+@findex gnus-article-emphasize
+@kindex W e (Summary)
+People commonly add emphasis to words in news articles by writing things
+like @samp{_this_} or @samp{*this*} or @samp{/this/}. Gnus can make
+this look nicer by running the article through the @kbd{W e}
+(@code{gnus-article-emphasize}) command.
+
+@vindex gnus-emphasis-alist
+How the emphasis is computed is controlled by the
+@code{gnus-emphasis-alist} variable. This is an alist where the first
+element is a regular expression to be matched. The second is a number
+that says what regular expression grouping is used to find the entire
+emphasized word. The third is a number that says what regexp grouping
+should be displayed and highlighted. (The text between these two
+groupings will be hidden.) The fourth is the face used for
+highlighting.
+
+@lisp
+(setq gnus-emphasis-alist
+ '(("_\\(\\w+\\)_" 0 1 gnus-emphasis-underline)
+ ("\\*\\(\\w+\\)\\*" 0 1 gnus-emphasis-bold)))
+@end lisp
+
+@cindex slash
+@cindex asterisk
+@cindex underline
+@cindex /
+@cindex *
+
+@vindex gnus-emphasis-underline
+@vindex gnus-emphasis-bold
+@vindex gnus-emphasis-italic
+@vindex gnus-emphasis-underline-bold
+@vindex gnus-emphasis-underline-italic
+@vindex gnus-emphasis-bold-italic
+@vindex gnus-emphasis-underline-bold-italic
+By default, there are seven rules, and they use the following faces:
+@code{gnus-emphasis-bold}, @code{gnus-emphasis-italic},
+@code{gnus-emphasis-underline}, @code{gnus-emphasis-bold-italic},
+@code{gnus-emphasis-underline-italic},
+@code{gnus-emphasis-underline-bold}, and
+@code{gnus-emphasis-underline-bold-italic}.
+
+If you want to change these faces, you can either use @kbd{M-x
+customize}, or you can use @code{copy-face}. For instance, if you want
+to make @code{gnus-emphasis-italic} use a red face instead, you could
+say something like:
+
+@lisp
+(copy-face 'red 'gnus-emphasis-italic)
+@end lisp
+
+@vindex gnus-group-highlight-words-alist
+
+If you want to highlight arbitrary words, you can use the
+@code{gnus-group-highlight-words-alist} variable, which uses the same
+syntax as @code{gnus-emphasis-alist}. The @code{highlight-words} group
+parameter (@pxref{Group Parameters}) can also be used.
+
+@xref{Customizing Articles}, for how to fontize articles automatically.
+
+
+@node Article Hiding
+@subsection Article Hiding
+@cindex article hiding
+
+Or rather, hiding certain things in each article. There usually is much
+too much cruft in most articles.
+
+@table @kbd
+
+@item W W a
+@kindex W W a (Summary)
+@findex gnus-article-hide
+Do quite a lot of hiding on the article buffer
+(@kbd{gnus-article-hide}). In particular, this function will hide
+headers, @acronym{PGP}, cited text and the signature.
+
+@item W W h
+@kindex W W h (Summary)
+@findex gnus-article-hide-headers
+Hide headers (@code{gnus-article-hide-headers}). @xref{Hiding
+Headers}.
+
+@item W W b
+@kindex W W b (Summary)
+@findex gnus-article-hide-boring-headers
+Hide headers that aren't particularly interesting
+(@code{gnus-article-hide-boring-headers}). @xref{Hiding Headers}.
+
+@item W W s
+@kindex W W s (Summary)
+@findex gnus-article-hide-signature
+Hide signature (@code{gnus-article-hide-signature}). @xref{Article
+Signature}.
+
+@item W W l
+@kindex W W l (Summary)
+@findex gnus-article-hide-list-identifiers
+@vindex gnus-list-identifiers
+Strip list identifiers specified in @code{gnus-list-identifiers}. These
+are strings some mailing list servers add to the beginning of all
+@code{Subject} headers---for example, @samp{[zebra 4711]}. Any leading
+@samp{Re: } is skipped before stripping. @code{gnus-list-identifiers}
+may not contain @code{\\(..\\)}.
+
+@table @code
+
+@item gnus-list-identifiers
+@vindex gnus-list-identifiers
+A regular expression that matches list identifiers to be removed from
+subject. This can also be a list of regular expressions.
+
+@end table
+
+@item W W P
+@kindex W W P (Summary)
+@findex gnus-article-hide-pem
+Hide @acronym{PEM} (privacy enhanced messages) cruft
+(@code{gnus-article-hide-pem}).
+
+@item W W B
+@kindex W W B (Summary)
+@findex gnus-article-strip-banner
+@vindex gnus-article-banner-alist
+@vindex gnus-article-address-banner-alist
+@cindex banner
+@cindex OneList
+@cindex stripping advertisements
+@cindex advertisements
+Strip the banner specified by the @code{banner} group parameter
+(@code{gnus-article-strip-banner}). This is mainly used to hide those
+annoying banners and/or signatures that some mailing lists and moderated
+groups adds to all the messages. The way to use this function is to add
+the @code{banner} group parameter (@pxref{Group Parameters}) to the
+group you want banners stripped from. The parameter either be a string,
+which will be interpreted as a regular expression matching text to be
+removed, or the symbol @code{signature}, meaning that the (last)
+signature should be removed, or other symbol, meaning that the
+corresponding regular expression in @code{gnus-article-banner-alist} is
+used.
+
+For instance:
+
+@lisp
+(setq gnus-article-banner-alist
+ ((googleGroups .
+ "^\n*--~--~---------\\(.+\n\\)+")))
+@end lisp
+
+Regardless of a group, you can hide things like advertisements only when
+the sender of an article has a certain mail address specified in
+@code{gnus-article-address-banner-alist}.
+
+@table @code
+
+@item gnus-article-address-banner-alist
+@vindex gnus-article-address-banner-alist
+Alist of mail addresses and banners. Each element has the form
+@code{(@var{address} . @var{banner})}, where @var{address} is a regexp
+matching a mail address in the From header, @var{banner} is one of a
+symbol @code{signature}, an item in @code{gnus-article-banner-alist},
+a regexp and @code{nil}. If @var{address} matches author's mail
+address, it will remove things like advertisements. For example, if a
+sender has the mail address @samp{hail@@yoo-hoo.co.jp} and there is a
+banner something like @samp{Do You Yoo-hoo!?} in all articles he
+sends, you can use the following element to remove them:
+
+@lisp
+("@@yoo-hoo\\.co\\.jp\\'" .
+ "\n_+\nDo You Yoo-hoo!\\?\n.*\n.*\n")
+@end lisp
+
+@end table
+
+@item W W c
+@kindex W W c (Summary)
+@findex gnus-article-hide-citation
+Hide citation (@code{gnus-article-hide-citation}). Some variables for
+customizing the hiding:
+
+@table @code
+
+@item gnus-cited-opened-text-button-line-format
+@itemx gnus-cited-closed-text-button-line-format
+@vindex gnus-cited-closed-text-button-line-format
+@vindex gnus-cited-opened-text-button-line-format
+Gnus adds buttons to show where the cited text has been hidden, and to
+allow toggle hiding the text. The format of the variable is specified
+by these format-like variable (@pxref{Formatting Variables}). These
+specs are valid:
+
+@table @samp
+@item b
+Starting point of the hidden text.
+@item e
+Ending point of the hidden text.
+@item l
+Number of characters in the hidden region.
+@item n
+Number of lines of hidden text.
+@end table
+
+@item gnus-cited-lines-visible
+@vindex gnus-cited-lines-visible
+The number of lines at the beginning of the cited text to leave
+shown. This can also be a cons cell with the number of lines at the top
+and bottom of the text, respectively, to remain visible.
+
+@end table
+
+@item W W C-c
+@kindex W W C-c (Summary)
+@findex gnus-article-hide-citation-maybe
+
+Hide citation (@code{gnus-article-hide-citation-maybe}) depending on the
+following two variables:
+
+@table @code
+@item gnus-cite-hide-percentage
+@vindex gnus-cite-hide-percentage
+If the cited text is of a bigger percentage than this variable (default
+50), hide the cited text.
+
+@item gnus-cite-hide-absolute
+@vindex gnus-cite-hide-absolute
+The cited text must have at least this length (default 10) before it
+is hidden.
+@end table
+
+@item W W C
+@kindex W W C (Summary)
+@findex gnus-article-hide-citation-in-followups
+Hide cited text in articles that aren't roots
+(@code{gnus-article-hide-citation-in-followups}). This isn't very
+useful as an interactive command, but might be a handy function to stick
+have happen automatically (@pxref{Customizing Articles}).
+
+@end table
+
+All these ``hiding'' commands are toggles, but if you give a negative
+prefix to these commands, they will show what they have previously
+hidden. If you give a positive prefix, they will always hide.
+
+Also @pxref{Article Highlighting} for further variables for
+citation customization.
+
+@xref{Customizing Articles}, for how to hide article elements
+automatically.
+
+
+@node Article Washing
+@subsection Article Washing
+@cindex washing
+@cindex article washing
+
+We call this ``article washing'' for a really good reason. Namely, the
+@kbd{A} key was taken, so we had to use the @kbd{W} key instead.
+
+@dfn{Washing} is defined by us as ``changing something from something to
+something else'', but normally results in something looking better.
+Cleaner, perhaps.
+
+@xref{Customizing Articles}, if you want to change how Gnus displays
+articles by default.
+
+@table @kbd
+
+@item C-u g
+This is not really washing, it's sort of the opposite of washing. If
+you type this, you see the article exactly as it exists on disk or on
+the server.
+
+@item g
+Force redisplaying of the current article
+(@code{gnus-summary-show-article}). This is also not really washing.
+If you type this, you see the article without any previously applied
+interactive Washing functions but with all default treatments
+(@pxref{Customizing Articles}).
+
+@item W l
+@kindex W l (Summary)
+@findex gnus-summary-stop-page-breaking
+Remove page breaks from the current article
+(@code{gnus-summary-stop-page-breaking}). @xref{Misc Article}, for page
+delimiters.
+
+@item W r
+@kindex W r (Summary)
+@findex gnus-summary-caesar-message
+@c @icon{gnus-summary-caesar-message}
+Do a Caesar rotate (rot13) on the article buffer
+(@code{gnus-summary-caesar-message}).
+Unreadable articles that tell you to read them with Caesar rotate or rot13.
+(Typically offensive jokes and such.)
+
+It's commonly called ``rot13'' because each letter is rotated 13
+positions in the alphabet, e.g., @samp{B} (letter #2) -> @samp{O} (letter
+#15). It is sometimes referred to as ``Caesar rotate'' because Caesar
+is rumored to have employed this form of, uh, somewhat weak encryption.
+
+@item W m
+@kindex W m (Summary)
+@findex gnus-summary-morse-message
+Morse decode the article buffer (@code{gnus-summary-morse-message}).
+
+@item W i
+@kindex W i (Summary)
+@findex gnus-summary-idna-message
+Decode IDNA encoded domain names in the current articles. IDNA
+encoded domain names looks like @samp{xn--bar}. If a string remain
+unencoded after running invoking this, it is likely an invalid IDNA
+string (@samp{xn--bar} is invalid). You must have GNU Libidn
+(@url{http://www.gnu.org/software/libidn/}) installed for this command
+to work.
+
+@item W t
+@item t
+@kindex W t (Summary)
+@kindex t (Summary)
+@findex gnus-summary-toggle-header
+Toggle whether to display all headers in the article buffer
+(@code{gnus-summary-toggle-header}).
+
+@item W v
+@kindex W v (Summary)
+@findex gnus-summary-verbose-headers
+Toggle whether to display all headers in the article buffer permanently
+(@code{gnus-summary-verbose-headers}).
+
+@item W o
+@kindex W o (Summary)
+@findex gnus-article-treat-overstrike
+Treat overstrike (@code{gnus-article-treat-overstrike}).
+
+@item W d
+@kindex W d (Summary)
+@findex gnus-article-treat-dumbquotes
+@vindex gnus-article-dumbquotes-map
+@cindex Smartquotes
+@cindex M****s*** sm*rtq**t*s
+@cindex Latin 1
+Treat M****s*** sm*rtq**t*s according to
+@code{gnus-article-dumbquotes-map}
+(@code{gnus-article-treat-dumbquotes}). Note that this function guesses
+whether a character is a sm*rtq**t* or not, so it should only be used
+interactively.
+
+Sm*rtq**t*s are M****s***'s unilateral extension to the character map in
+an attempt to provide more quoting characters. If you see something
+like @code{\222} or @code{\264} where you're expecting some kind of
+apostrophe or quotation mark, then try this wash.
+
+@item W U
+@kindex W U (Summary)
+@findex gnus-article-treat-non-ascii
+@cindex Unicode
+@cindex Non-@acronym{ASCII}
+Translate many non-@acronym{ASCII} characters into their
+@acronym{ASCII} equivalents (@code{gnus-article-treat-non-ascii}).
+This is mostly useful if you're on a terminal that has a limited font
+and doesn't show accented characters, ``advanced'' punctuation, and the
+like. For instance, @samp{»} is translated into @samp{>>}, and so on.
+
+@item W Y f
+@kindex W Y f (Summary)
+@findex gnus-article-outlook-deuglify-article
+@cindex Outlook Express
+Full deuglify of broken Outlook (Express) articles: Treat dumbquotes,
+unwrap lines, repair attribution and rearrange citation.
+(@code{gnus-article-outlook-deuglify-article}).
+
+@item W Y u
+@kindex W Y u (Summary)
+@findex gnus-article-outlook-unwrap-lines
+@vindex gnus-outlook-deuglify-unwrap-min
+@vindex gnus-outlook-deuglify-unwrap-max
+Unwrap lines that appear to be wrapped citation lines. You can control
+what lines will be unwrapped by frobbing
+@code{gnus-outlook-deuglify-unwrap-min} and
+@code{gnus-outlook-deuglify-unwrap-max}, indicating the minimum and
+maximum length of an unwrapped citation line.
+(@code{gnus-article-outlook-unwrap-lines}).
+
+@item W Y a
+@kindex W Y a (Summary)
+@findex gnus-article-outlook-repair-attribution
+Repair a broken attribution line.@*
+(@code{gnus-article-outlook-repair-attribution}).
+
+@item W Y c
+@kindex W Y c (Summary)
+@findex gnus-article-outlook-rearrange-citation
+Repair broken citations by rearranging the text.
+(@code{gnus-article-outlook-rearrange-citation}).
+
+@item W w
+@kindex W w (Summary)
+@findex gnus-article-fill-cited-article
+Do word wrap (@code{gnus-article-fill-cited-article}).
+
+You can give the command a numerical prefix to specify the width to use
+when filling.
+
+@item W Q
+@kindex W Q (Summary)
+@findex gnus-article-fill-long-lines
+Fill long lines (@code{gnus-article-fill-long-lines}).
+
+@item W C
+@kindex W C (Summary)
+@findex gnus-article-capitalize-sentences
+Capitalize the first word in each sentence
+(@code{gnus-article-capitalize-sentences}).
+
+@item W c
+@kindex W c (Summary)
+@findex gnus-article-remove-cr
+Translate CRLF pairs (i.e., @samp{^M}s on the end of the lines) into LF
+(this takes care of DOS line endings), and then translate any remaining
+CRs into LF (this takes care of Mac line endings)
+(@code{gnus-article-remove-cr}).
+
+@item W q
+@kindex W q (Summary)
+@findex gnus-article-de-quoted-unreadable
+Treat quoted-printable (@code{gnus-article-de-quoted-unreadable}).
+Quoted-Printable is one common @acronym{MIME} encoding employed when
+sending non-@acronym{ASCII} (i.e., 8-bit) articles. It typically
+makes strings like @samp{déjà vu} look like @samp{d=E9j=E0 vu},
+which doesn't look very readable to me. Note that this is usually
+done automatically by Gnus if the message in question has a
+@code{Content-Transfer-Encoding} header that says that this encoding
+has been done. If a prefix is given, a charset will be asked for.
+
+@item W 6
+@kindex W 6 (Summary)
+@findex gnus-article-de-base64-unreadable
+Treat base64 (@code{gnus-article-de-base64-unreadable}). Base64 is
+one common @acronym{MIME} encoding employed when sending
+non-@acronym{ASCII} (i.e., 8-bit) articles. Note that this is
+usually done automatically by Gnus if the message in question has a
+@code{Content-Transfer-Encoding} header that says that this encoding
+has been done. If a prefix is given, a charset will be asked for.
+
+@item W Z
+@kindex W Z (Summary)
+@findex gnus-article-decode-HZ
+Treat HZ or HZP (@code{gnus-article-decode-HZ}). HZ (or HZP) is one
+common encoding employed when sending Chinese articles. It typically
+makes strings look like @samp{~@{<:Ky2;S@{#,NpJ)l6HK!#~@}}.
+
+@item W A
+@kindex W A (Summary)
+@findex gnus-article-treat-ansi-sequences
+@cindex @acronym{ANSI} control sequences
+Translate @acronym{ANSI} SGR control sequences into overlays or
+extents (@code{gnus-article-treat-ansi-sequences}). @acronym{ANSI}
+sequences are used in some Chinese hierarchies for highlighting.
+
+@item W u
+@kindex W u (Summary)
+@findex gnus-article-unsplit-urls
+Remove newlines from within URLs. Some mailers insert newlines into
+outgoing email messages to keep lines short. This reformatting can
+split long URLs onto multiple lines. Repair those URLs by removing
+the newlines (@code{gnus-article-unsplit-urls}).
+
+@item W h
+@kindex W h (Summary)
+@findex gnus-article-wash-html
+Treat @acronym{HTML} (@code{gnus-article-wash-html}). Note that this is
+usually done automatically by Gnus if the message in question has a
+@code{Content-Type} header that says that the message is @acronym{HTML}.
+
+If a prefix is given, a charset will be asked for. If it is a number,
+the charset defined in @code{gnus-summary-show-article-charset-alist}
+(@pxref{Paging the Article}) will be used.
+
+The default is to use the function specified by
+@code{mm-text-html-renderer} (@pxref{Display Customization, ,Display
+Customization, emacs-mime, The Emacs MIME Manual}) to convert the
+@acronym{HTML}. Pre-defined functions you can use include:
+
+@table @code
+@item shr
+Use Gnus simple html renderer.
+
+@item gnus-w3m
+Use Gnus rendered based on w3m.
+
+@item w3m
+Use @uref{http://emacs-w3m.namazu.org/, emacs-w3m}.
+
+@item w3m-standalone
+Use @uref{http://w3m.sourceforge.net/, w3m}.
+
+@item links
+Use @uref{http://links.sf.net/, Links}.
+
+@item lynx
+Use @uref{http://lynx.isc.org/, Lynx}.
+
+@item html2text
+Use html2text---a simple @acronym{HTML} converter included with Gnus.
+
+@end table
+
+@item W b
+@kindex W b (Summary)
+@findex gnus-article-add-buttons
+Add clickable buttons to the article (@code{gnus-article-add-buttons}).
+@xref{Article Buttons}.
+
+@item W B
+@kindex W B (Summary)
+@findex gnus-article-add-buttons-to-head
+Add clickable buttons to the article headers
+(@code{gnus-article-add-buttons-to-head}).
+
+@item W p
+@kindex W p (Summary)
+@findex gnus-article-verify-x-pgp-sig
+Verify a signed control message
+(@code{gnus-article-verify-x-pgp-sig}). Control messages such as
+@code{newgroup} and @code{checkgroups} are usually signed by the
+hierarchy maintainer. You need to add the @acronym{PGP} public key of
+the maintainer to your keyring to verify the
+message.@footnote{@acronym{PGP} keys for many hierarchies are
+available at @uref{ftp://ftp.isc.org/pub/pgpcontrol/README.html}}
+
+@item W s
+@kindex W s (Summary)
+@findex gnus-summary-force-verify-and-decrypt
+Verify a signed (@acronym{PGP}, @acronym{PGP/MIME} or
+@acronym{S/MIME}) message
+(@code{gnus-summary-force-verify-and-decrypt}). @xref{Security}.
+
+@item W a
+@kindex W a (Summary)
+@findex gnus-article-strip-headers-in-body
+Strip headers like the @code{X-No-Archive} header from the beginning of
+article bodies (@code{gnus-article-strip-headers-in-body}).
+
+@item W E l
+@kindex W E l (Summary)
+@findex gnus-article-strip-leading-blank-lines
+Remove all blank lines from the beginning of the article
+(@code{gnus-article-strip-leading-blank-lines}).
+
+@item W E m
+@kindex W E m (Summary)
+@findex gnus-article-strip-multiple-blank-lines
+Replace all blank lines with empty lines and then all multiple empty
+lines with a single empty line.
+(@code{gnus-article-strip-multiple-blank-lines}).
+
+@item W E t
+@kindex W E t (Summary)
+@findex gnus-article-remove-trailing-blank-lines
+Remove all blank lines at the end of the article
+(@code{gnus-article-remove-trailing-blank-lines}).
+
+@item W E a
+@kindex W E a (Summary)
+@findex gnus-article-strip-blank-lines
+Do all the three commands above
+(@code{gnus-article-strip-blank-lines}).
+
+@item W E A
+@kindex W E A (Summary)
+@findex gnus-article-strip-all-blank-lines
+Remove all blank lines
+(@code{gnus-article-strip-all-blank-lines}).
+
+@item W E s
+@kindex W E s (Summary)
+@findex gnus-article-strip-leading-space
+Remove all white space from the beginning of all lines of the article
+body (@code{gnus-article-strip-leading-space}).
+
+@item W E e
+@kindex W E e (Summary)
+@findex gnus-article-strip-trailing-space
+Remove all white space from the end of all lines of the article
+body (@code{gnus-article-strip-trailing-space}).
+
+@end table
+
+@xref{Customizing Articles}, for how to wash articles automatically.
+
+
+@node Article Header
+@subsection Article Header
+
+These commands perform various transformations of article header.
+
+@table @kbd
+
+@item W G u
+@kindex W G u (Summary)
+@findex gnus-article-treat-unfold-headers
+Unfold folded header lines (@code{gnus-article-treat-unfold-headers}).
+
+@item W G n
+@kindex W G n (Summary)
+@findex gnus-article-treat-fold-newsgroups
+Fold the @code{Newsgroups} and @code{Followup-To} headers
+(@code{gnus-article-treat-fold-newsgroups}).
+
+@item W G f
+@kindex W G f (Summary)
+@findex gnus-article-treat-fold-headers
+Fold all the message headers
+(@code{gnus-article-treat-fold-headers}).
+
+@item W E w
+@kindex W E w (Summary)
+@findex gnus-article-remove-leading-whitespace
+Remove excessive whitespace from all headers
+(@code{gnus-article-remove-leading-whitespace}).
+
+@end table
+
+
+@node Article Buttons
+@subsection Article Buttons
+@cindex buttons
+
+People often include references to other stuff in articles, and it would
+be nice if Gnus could just fetch whatever it is that people talk about
+with the minimum of fuzz when you hit @kbd{RET} or use the middle mouse
+button on these references.
+
+@vindex gnus-button-man-handler
+Gnus adds @dfn{buttons} to certain standard references by default:
+Well-formed URLs, mail addresses, Message-IDs, Info links, man pages and
+Emacs or Gnus related references. This is controlled by two variables,
+one that handles article bodies and one that handles article heads:
+
+@table @code
+
+@item gnus-button-alist
+@vindex gnus-button-alist
+This is an alist where each entry has this form:
+
+@lisp
+(@var{regexp} @var{button-par} @var{use-p} @var{function} @var{data-par})
+@end lisp
+
+@table @var
+
+@item regexp
+All text that match this regular expression (case insensitive) will be
+considered an external reference. Here's a typical regexp that matches
+embedded URLs: @samp{<URL:\\([^\n\r>]*\\)>}. This can also be a
+variable containing a regexp, useful variables to use include
+@code{gnus-button-url-regexp} and @code{gnus-button-mid-or-mail-regexp}.
+
+@item button-par
+Gnus has to know which parts of the matches is to be highlighted. This
+is a number that says what sub-expression of the regexp is to be
+highlighted. If you want it all highlighted, you use 0 here.
+
+@item use-p
+This form will be @code{eval}ed, and if the result is non-@code{nil},
+this is considered a match. This is useful if you want extra sifting to
+avoid false matches. Often variables named
+@code{gnus-button-@var{*}-level} are used here, @xref{Article Button
+Levels}, but any other form may be used too.
+
+@c @code{use-p} is @code{eval}ed only if @code{regexp} matches.
+
+@item function
+This function will be called when you click on this button.
+
+@item data-par
+As with @var{button-par}, this is a sub-expression number, but this one
+says which part of the match is to be sent as data to @var{function}.
+
+@end table
+
+So the full entry for buttonizing URLs is then
+
+@lisp
+("<URL:\\([^\n\r>]*\\)>" 0 t gnus-button-url 1)
+@end lisp
+
+@item gnus-header-button-alist
+@vindex gnus-header-button-alist
+This is just like the other alist, except that it is applied to the
+article head only, and that each entry has an additional element that is
+used to say what headers to apply the buttonize coding to:
+
+@lisp
+(@var{header} @var{regexp} @var{button-par} @var{use-p} @var{function} @var{data-par})
+@end lisp
+
+@var{header} is a regular expression.
+@end table
+
+@subsubsection Related variables and functions
+
+@table @code
+@item gnus-button-@var{*}-level
+@xref{Article Button Levels}.
+
+@c Stuff related to gnus-button-browse-level
+
+@item gnus-button-url-regexp
+@vindex gnus-button-url-regexp
+A regular expression that matches embedded URLs. It is used in the
+default values of the variables above.
+
+@c Stuff related to gnus-button-man-level
+
+@item gnus-button-man-handler
+@vindex gnus-button-man-handler
+The function to use for displaying man pages. It must take at least one
+argument with a string naming the man page.
+
+@c Stuff related to gnus-button-message-level
+
+@item gnus-button-mid-or-mail-regexp
+@vindex gnus-button-mid-or-mail-regexp
+Regular expression that matches a message ID or a mail address.
+
+@item gnus-button-prefer-mid-or-mail
+@vindex gnus-button-prefer-mid-or-mail
+This variable determines what to do when the button on a string as
+@samp{foo123@@bar.invalid} is pushed. Strings like this can be either a
+message ID or a mail address. If it is one of the symbols @code{mid} or
+@code{mail}, Gnus will always assume that the string is a message ID or
+a mail address, respectively. If this variable is set to the symbol
+@code{ask}, always query the user what to do. If it is a function, this
+function will be called with the string as its only argument. The
+function must return @code{mid}, @code{mail}, @code{invalid} or
+@code{ask}. The default value is the function
+@code{gnus-button-mid-or-mail-heuristic}.
+
+@item gnus-button-mid-or-mail-heuristic
+@findex gnus-button-mid-or-mail-heuristic
+Function that guesses whether its argument is a message ID or a mail
+address. Returns @code{mid} if it's a message IDs, @code{mail} if
+it's a mail address, @code{ask} if unsure and @code{invalid} if the
+string is invalid.
+
+@item gnus-button-mid-or-mail-heuristic-alist
+@vindex gnus-button-mid-or-mail-heuristic-alist
+An alist of @code{(RATE . REGEXP)} pairs used by the function
+@code{gnus-button-mid-or-mail-heuristic}.
+
+@c Misc stuff
+
+@item gnus-article-button-face
+@vindex gnus-article-button-face
+Face used on buttons.
+
+@item gnus-article-mouse-face
+@vindex gnus-article-mouse-face
+Face used when the mouse cursor is over a button.
+
+@end table
+
+@xref{Customizing Articles}, for how to buttonize articles automatically.
+
+
+@node Article Button Levels
+@subsection Article button levels
+@cindex button levels
+The higher the value of the variables @code{gnus-button-@var{*}-level},
+the more buttons will appear. If the level is zero, no corresponding
+buttons are displayed. With the default value (which is 5) you should
+already see quite a lot of buttons. With higher levels, you will see
+more buttons, but you may also get more false positives. To avoid them,
+you can set the variables @code{gnus-button-@var{*}-level} local to
+specific groups (@pxref{Group Parameters}). Here's an example for the
+variable @code{gnus-parameters}:
+
+@lisp
+;; @r{increase @code{gnus-button-*-level} in some groups:}
+(setq gnus-parameters
+ '(("\\<\\(emacs\\|gnus\\)\\>" (gnus-button-emacs-level 10))
+ ("\\<unix\\>" (gnus-button-man-level 10))
+ ("\\<tex\\>" (gnus-button-tex-level 10))))
+@end lisp
+
+@table @code
+
+@item gnus-button-browse-level
+@vindex gnus-button-browse-level
+Controls the display of references to message IDs, mail addresses and
+news URLs. Related variables and functions include
+@code{gnus-button-url-regexp}, @code{browse-url}, and
+@code{browse-url-browser-function}.
+
+@item gnus-button-emacs-level
+@vindex gnus-button-emacs-level
+Controls the display of Emacs or Gnus references. Related functions are
+@code{gnus-button-handle-custom},
+@code{gnus-button-handle-describe-function},
+@code{gnus-button-handle-describe-variable},
+@code{gnus-button-handle-symbol},
+@code{gnus-button-handle-describe-key},
+@code{gnus-button-handle-apropos},
+@code{gnus-button-handle-apropos-command},
+@code{gnus-button-handle-apropos-variable},
+@code{gnus-button-handle-apropos-documentation}, and
+@code{gnus-button-handle-library}.
+
+@item gnus-button-man-level
+@vindex gnus-button-man-level
+Controls the display of references to (Unix) man pages.
+See @code{gnus-button-man-handler}.
+
+@item gnus-button-message-level
+@vindex gnus-button-message-level
+Controls the display of message IDs, mail addresses and news URLs.
+Related variables and functions include
+@code{gnus-button-mid-or-mail-regexp},
+@code{gnus-button-prefer-mid-or-mail},
+@code{gnus-button-mid-or-mail-heuristic}, and
+@code{gnus-button-mid-or-mail-heuristic-alist}.
+
+@end table
+
+
+@node Article Date
+@subsection Article Date
+
+The date is most likely generated in some obscure timezone you've never
+heard of, so it's quite nice to be able to find out what the time was
+when the article was sent.
+
+@table @kbd
+
+@item W T u
+@kindex W T u (Summary)
+@findex gnus-article-date-ut
+Display the date in UT (aka. GMT, aka ZULU)
+(@code{gnus-article-date-ut}).
+
+@item W T i
+@kindex W T i (Summary)
+@findex gnus-article-date-iso8601
+@cindex ISO 8601
+Display the date in international format, aka. ISO 8601
+(@code{gnus-article-date-iso8601}).
+
+@item W T l
+@kindex W T l (Summary)
+@findex gnus-article-date-local
+Display the date in the local timezone (@code{gnus-article-date-local}).
+
+@item W T p
+@kindex W T p (Summary)
+@findex gnus-article-date-english
+Display the date in a format that's easily pronounceable in English
+(@code{gnus-article-date-english}).
+
+@item W T s
+@kindex W T s (Summary)
+@vindex gnus-article-time-format
+@findex gnus-article-date-user
+@findex format-time-string
+Display the date using a user-defined format
+(@code{gnus-article-date-user}). The format is specified by the
+@code{gnus-article-time-format} variable, and is a string that's passed
+to @code{format-time-string}. See the documentation of that variable
+for a list of possible format specs.
+
+@item W T e
+@kindex W T e (Summary)
+@findex gnus-article-date-lapsed
+@findex gnus-start-date-timer
+@findex gnus-stop-date-timer
+Say how much time has elapsed between the article was posted and now
+(@code{gnus-article-date-lapsed}). It looks something like:
+
+@example
+Date: 6 weeks, 4 days, 1 hour, 3 minutes, 8 seconds ago
+@end example
+
+To make this line updated continually, set the
+@code{gnus-article-update-date-headers} variable to the frequency in
+seconds (the default is @code{nil}).
+
+@item W T o
+@kindex W T o (Summary)
+@findex gnus-article-date-original
+Display the original date (@code{gnus-article-date-original}). This can
+be useful if you normally use some other conversion function and are
+worried that it might be doing something totally wrong. Say, claiming
+that the article was posted in 1854. Although something like that is
+@emph{totally} impossible. Don't you trust me? *titter*
+
+@end table
+
+@xref{Customizing Articles}, for how to display the date in your
+preferred format automatically.
+
+
+@node Article Display
+@subsection Article Display
+@cindex picons
+@cindex x-face
+@cindex smileys
+@cindex gravatars
+
+These commands add various frivolous display gimmicks to the article
+buffer in Emacs versions that support them.
+
+@code{X-Face} headers are small black-and-white images supplied by the
+message headers (@pxref{X-Face}).
+
+@code{Face} headers are small colored images supplied by the message
+headers (@pxref{Face}).
+
+Smileys are those little @samp{:-)} symbols that people like to litter
+their messages with (@pxref{Smileys}).
+
+Picons, on the other hand, reside on your own system, and Gnus will
+try to match the headers to what you have (@pxref{Picons}).
+
+Gravatars reside on-line and are fetched from
+@uref{http://www.gravatar.com/} (@pxref{Gravatars}).
+
+All these functions are toggles---if the elements already exist,
+they'll be removed.
+
+@table @kbd
+@item W D x
+@kindex W D x (Summary)
+@findex gnus-article-display-x-face
+Display an @code{X-Face} in the @code{From} header.
+(@code{gnus-article-display-x-face}).
+
+@item W D d
+@kindex W D d (Summary)
+@findex gnus-article-display-face
+Display a @code{Face} in the @code{From} header.
+(@code{gnus-article-display-face}).
+
+@item W D s
+@kindex W D s (Summary)
+@findex gnus-treat-smiley
+Display smileys (@code{gnus-treat-smiley}).
+
+@item W D f
+@kindex W D f (Summary)
+@findex gnus-treat-from-picon
+Piconify the @code{From} header (@code{gnus-treat-from-picon}).
+
+@item W D m
+@kindex W D m (Summary)
+@findex gnus-treat-mail-picon
+Piconify all mail headers (i.e., @code{Cc}, @code{To})
+(@code{gnus-treat-mail-picon}).
+
+@item W D n
+@kindex W D n (Summary)
+@findex gnus-treat-newsgroups-picon
+Piconify all news headers (i.e., @code{Newsgroups} and
+@code{Followup-To}) (@code{gnus-treat-newsgroups-picon}).
+
+@item W D g
+@kindex W D g (Summary)
+@findex gnus-treat-from-gravatar
+Gravatarify the @code{From} header (@code{gnus-treat-from-gravatar}).
+
+@item W D h
+@kindex W D h (Summary)
+@findex gnus-treat-mail-gravatar
+Gravatarify all mail headers (i.e., @code{Cc}, @code{To})
+(@code{gnus-treat-from-gravatar}).
+
+@item W D D
+@kindex W D D (Summary)
+@findex gnus-article-remove-images
+Remove all images from the article buffer
+(@code{gnus-article-remove-images}).
+
+@item W D W
+@kindex W D W (Summary)
+@findex gnus-html-show-images
+If you're reading an @acronym{HTML} article rendered with
+@code{gnus-article-html}, then you can insert any blocked images in
+the buffer with this command.
+(@code{gnus-html-show-images}).
+
+@end table
+
+
+
+@node Article Signature
+@subsection Article Signature
+@cindex signatures
+@cindex article signature
+
+@vindex gnus-signature-separator
+Each article is divided into two parts---the head and the body. The
+body can be divided into a signature part and a text part. The variable
+that says what is to be considered a signature is
+@code{gnus-signature-separator}. This is normally the standard
+@samp{^-- $} as mandated by son-of-RFC 1036. However, many people use
+non-standard signature separators, so this variable can also be a list
+of regular expressions to be tested, one by one. (Searches are done
+from the end of the body towards the beginning.) One likely value is:
+
+@lisp
+(setq gnus-signature-separator
+ '("^-- $" ; @r{The standard}
+ "^-- *$" ; @r{A common mangling}
+ "^-------*$" ; @r{Many people just use a looong}
+ ; @r{line of dashes. Shame!}
+ "^ *--------*$" ; @r{Double-shame!}
+ "^________*$" ; @r{Underscores are also popular}
+ "^========*$")) ; @r{Pervert!}
+@end lisp
+
+The more permissive you are, the more likely it is that you'll get false
+positives.
+
+@vindex gnus-signature-limit
+@code{gnus-signature-limit} provides a limit to what is considered a
+signature when displaying articles.
+
+@enumerate
+@item
+If it is an integer, no signature may be longer (in characters) than
+that integer.
+@item
+If it is a floating point number, no signature may be longer (in lines)
+than that number.
+@item
+If it is a function, the function will be called without any parameters,
+and if it returns @code{nil}, there is no signature in the buffer.
+@item
+If it is a string, it will be used as a regexp. If it matches, the text
+in question is not a signature.
+@end enumerate
+
+This variable can also be a list where the elements may be of the types
+listed above. Here's an example:
+
+@lisp
+(setq gnus-signature-limit
+ '(200.0 "^---*Forwarded article"))
+@end lisp
+
+This means that if there are more than 200 lines after the signature
+separator, or the text after the signature separator is matched by
+the regular expression @samp{^---*Forwarded article}, then it isn't a
+signature after all.
+
+
+@node Article Miscellanea
+@subsection Article Miscellanea
+
+@table @kbd
+@item A t
+@kindex A t (Summary)
+@findex gnus-article-babel
+Translate the article from one language to another
+(@code{gnus-article-babel}).
+
+@end table
+
+
+@node MIME Commands
+@section MIME Commands
+@cindex MIME decoding
+@cindex attachments
+@cindex viewing attachments
+
+The following commands all understand the numerical prefix. For
+instance, @kbd{3 K v} means ``view the third @acronym{MIME} part''.
+
+@table @kbd
+@item b
+@itemx K v
+@kindex b (Summary)
+@kindex K v (Summary)
+View the @acronym{MIME} part.
+
+@item K o
+@kindex K o (Summary)
+Save the @acronym{MIME} part.
+
+@item K O
+@kindex K O (Summary)
+Prompt for a file name, then save the @acronym{MIME} part and strip it
+from the article. The stripped @acronym{MIME} object will be referred
+via the message/external-body @acronym{MIME} type.
+
+@item K r
+@kindex K r (Summary)
+Replace the @acronym{MIME} part with an external body.
+
+@item K d
+@kindex K d (Summary)
+Delete the @acronym{MIME} part and add some information about the
+removed part.
+
+@item K c
+@kindex K c (Summary)
+Copy the @acronym{MIME} part.
+
+@item K e
+@kindex K e (Summary)
+View the @acronym{MIME} part externally.
+
+@item K i
+@kindex K i (Summary)
+View the @acronym{MIME} part internally.
+
+@item K |
+@kindex K | (Summary)
+Pipe the @acronym{MIME} part to an external command.
+@end table
+
+The rest of these @acronym{MIME} commands do not use the numerical prefix in
+the same manner:
+
+@table @kbd
+@item K H
+@kindex K H (Summary)
+@findex gnus-article-browse-html-article
+View @samp{text/html} parts of the current article with a WWW browser.
+Inline images embedded in a message using the @code{cid} scheme, as they
+are generally considered to be safe, will be processed properly. The
+message header is added to the beginning of every @acronym{HTML} part
+unless the prefix argument is given.
+
+Warning: Spammers use links to images (using the @code{http} scheme) in
+@acronym{HTML} articles to verify whether you have read the message. As
+this command passes the @acronym{HTML} content to the browser without
+eliminating these ``web bugs'' you should only use it for mails from
+trusted senders.
+
+If you always want to display @acronym{HTML} parts in the browser, set
+@code{mm-text-html-renderer} to @code{nil}.
+
+This command creates temporary files to pass @acronym{HTML} contents
+including images if any to the browser, and deletes them when exiting
+the group (if you want).
+
+@item K b
+@kindex K b (Summary)
+Make all the @acronym{MIME} parts have buttons in front of them. This is
+mostly useful if you wish to save (or perform other actions) on inlined
+parts.
+
+@item W M h
+@kindex W M h (Summary)
+@findex gnus-mime-buttonize-attachments-in-header
+@vindex gnus-mime-display-attachment-buttons-in-header
+Display @acronym{MIME} part buttons in the end of the header of an
+article (@code{gnus-mime-buttonize-attachments-in-header}). This
+command toggles the display. Note that buttons to be added to the
+header are only the ones that aren't inlined in the body. If you want
+those buttons always to be displayed, set
+@code{gnus-mime-display-attachment-buttons-in-header} to non-@code{nil}.
+The default is @code{t}. To change the appearance of buttons, customize
+@code{gnus-header-face-alist}.
+
+@item K m
+@kindex K m (Summary)
+@findex gnus-summary-repair-multipart
+Some multipart messages are transmitted with missing or faulty headers.
+This command will attempt to ``repair'' these messages so that they can
+be viewed in a more pleasant manner
+(@code{gnus-summary-repair-multipart}).
+
+@item X m
+@kindex X m (Summary)
+@findex gnus-summary-save-parts
+Save all parts matching a @acronym{MIME} type to a directory
+(@code{gnus-summary-save-parts}). Understands the process/prefix
+convention (@pxref{Process/Prefix}).
+
+@item M-t
+@kindex M-t (Summary)
+@findex gnus-summary-toggle-display-buttonized
+Toggle the buttonized display of the article buffer
+(@code{gnus-summary-toggle-display-buttonized}).
+
+@item W M w
+@kindex W M w (Summary)
+@findex gnus-article-decode-mime-words
+Decode RFC 2047-encoded words in the article headers
+(@code{gnus-article-decode-mime-words}).
+
+@item W M c
+@kindex W M c (Summary)
+@findex gnus-article-decode-charset
+Decode encoded article bodies as well as charsets
+(@code{gnus-article-decode-charset}).
+
+This command looks in the @code{Content-Type} header to determine the
+charset. If there is no such header in the article, you can give it a
+prefix, which will prompt for the charset to decode as. In regional
+groups where people post using some common encoding (but do not
+include @acronym{MIME} headers), you can set the @code{charset} group/topic
+parameter to the required charset (@pxref{Group Parameters}).
+
+@item W M v
+@kindex W M v (Summary)
+@findex gnus-mime-view-all-parts
+View all the @acronym{MIME} parts in the current article
+(@code{gnus-mime-view-all-parts}).
+
+@end table
+
+Relevant variables:
+
+@table @code
+@item gnus-ignored-mime-types
+@vindex gnus-ignored-mime-types
+This is a list of regexps. @acronym{MIME} types that match a regexp from
+this list will be completely ignored by Gnus. The default value is
+@code{nil}.
+
+To have all Vcards be ignored, you'd say something like this:
+
+@lisp
+(setq gnus-ignored-mime-types
+ '("text/x-vcard"))
+@end lisp
+
+@item gnus-article-loose-mime
+@vindex gnus-article-loose-mime
+If non-@code{nil}, Gnus won't require the @samp{MIME-Version} header
+before interpreting the message as a @acronym{MIME} message. This helps
+when reading messages from certain broken mail user agents. The
+default is @code{t}.
+
+@item gnus-article-emulate-mime
+@vindex gnus-article-emulate-mime
+@cindex uuencode
+@cindex yEnc
+There are other, non-@acronym{MIME} encoding methods used. The most common
+is @samp{uuencode}, but yEncode is also getting to be popular. If
+this variable is non-@code{nil}, Gnus will look in message bodies to
+see if it finds these encodings, and if so, it'll run them through the
+Gnus @acronym{MIME} machinery. The default is @code{t}. Only
+single-part yEnc encoded attachments can be decoded. There's no support
+for encoding in Gnus.
+
+@item gnus-unbuttonized-mime-types
+@vindex gnus-unbuttonized-mime-types
+This is a list of regexps. @acronym{MIME} types that match a regexp from
+this list won't have @acronym{MIME} buttons inserted unless they aren't
+displayed or this variable is overridden by
+@code{gnus-buttonized-mime-types}. The default value is
+@code{(".*/.*")}. This variable is only used when
+@code{gnus-inhibit-mime-unbuttonizing} is @code{nil}.
+
+@item gnus-buttonized-mime-types
+@vindex gnus-buttonized-mime-types
+This is a list of regexps. @acronym{MIME} types that match a regexp from
+this list will have @acronym{MIME} buttons inserted unless they aren't
+displayed. This variable overrides
+@code{gnus-unbuttonized-mime-types}. The default value is @code{nil}.
+This variable is only used when @code{gnus-inhibit-mime-unbuttonizing}
+is @code{nil}.
+
+E.g., to see security buttons but no other buttons, you could set this
+variable to @code{("multipart/signed")} and leave
+@code{gnus-unbuttonized-mime-types} at the default value.
+
+You could also add @code{"multipart/alternative"} to this list to
+display radio buttons that allow you to choose one of two media types
+those mails include. See also @code{mm-discouraged-alternatives}
+(@pxref{Display Customization, ,Display Customization, emacs-mime, The
+Emacs MIME Manual}).
+
+@item gnus-inhibit-mime-unbuttonizing
+@vindex gnus-inhibit-mime-unbuttonizing
+If this is non-@code{nil}, then all @acronym{MIME} parts get buttons. The
+default value is @code{nil}.
+
+@item gnus-article-mime-part-function
+@vindex gnus-article-mime-part-function
+For each @acronym{MIME} part, this function will be called with the @acronym{MIME}
+handle as the parameter. The function is meant to be used to allow
+users to gather information from the article (e.g., add Vcard info to
+the bbdb database) or to do actions based on parts (e.g., automatically
+save all jpegs into some directory).
+
+Here's an example function the does the latter:
+
+@lisp
+(defun my-save-all-jpeg-parts (handle)
+ (when (equal (car (mm-handle-type handle)) "image/jpeg")
+ (with-temp-buffer
+ (insert (mm-get-part handle))
+ (write-region (point-min) (point-max)
+ (read-file-name "Save jpeg to: ")))))
+(setq gnus-article-mime-part-function
+ 'my-save-all-jpeg-parts)
+@end lisp
+
+@vindex gnus-mime-multipart-functions
+@item gnus-mime-multipart-functions
+Alist of @acronym{MIME} multipart types and functions to handle them.
+
+@vindex gnus-mime-display-multipart-alternative-as-mixed
+@item gnus-mime-display-multipart-alternative-as-mixed
+Display "multipart/alternative" parts as "multipart/mixed".
+
+@vindex gnus-mime-display-multipart-related-as-mixed
+@item gnus-mime-display-multipart-related-as-mixed
+Display "multipart/related" parts as "multipart/mixed".
+
+If displaying @samp{text/html} is discouraged, see
+@code{mm-discouraged-alternatives}, images or other material inside a
+"multipart/related" part might be overlooked when this variable is
+@code{nil}. @ref{Display Customization, Display Customization, ,
+emacs-mime, Emacs-Mime Manual}.
+
+@vindex gnus-mime-display-multipart-as-mixed
+@item gnus-mime-display-multipart-as-mixed
+Display "multipart" parts as "multipart/mixed". If @code{t}, it
+overrides @code{nil} values of
+@code{gnus-mime-display-multipart-alternative-as-mixed} and
+@code{gnus-mime-display-multipart-related-as-mixed}.
+
+@vindex mm-file-name-rewrite-functions
+@item mm-file-name-rewrite-functions
+List of functions used for rewriting file names of @acronym{MIME} parts.
+Each function takes a file name as input and returns a file name.
+
+Ready-made functions include@*
+@code{mm-file-name-delete-whitespace},
+@code{mm-file-name-trim-whitespace},
+@code{mm-file-name-collapse-whitespace}, and
+@code{mm-file-name-replace-whitespace}. The later uses the value of
+the variable @code{mm-file-name-replace-whitespace} to replace each
+whitespace character in a file name with that string; default value
+is @code{"_"} (a single underscore).
+@findex mm-file-name-delete-whitespace
+@findex mm-file-name-trim-whitespace
+@findex mm-file-name-collapse-whitespace
+@findex mm-file-name-replace-whitespace
+@vindex mm-file-name-replace-whitespace
+
+The standard functions @code{capitalize}, @code{downcase},
+@code{upcase}, and @code{upcase-initials} may be useful, too.
+
+Everybody knows that whitespace characters in file names are evil,
+except those who don't know. If you receive lots of attachments from
+such unenlightened users, you can make live easier by adding
+
+@lisp
+(setq mm-file-name-rewrite-functions
+ '(mm-file-name-trim-whitespace
+ mm-file-name-collapse-whitespace
+ mm-file-name-replace-whitespace))
+@end lisp
+
+@noindent
+to your @file{~/.gnus.el} file.
+
+@end table
+
+
+@node Charsets
+@section Charsets
+@cindex charsets
+
+People use different charsets, and we have @acronym{MIME} to let us know what
+charsets they use. Or rather, we wish we had. Many people use
+newsreaders and mailers that do not understand or use @acronym{MIME}, and
+just send out messages without saying what character sets they use. To
+help a bit with this, some local news hierarchies have policies that say
+what character set is the default. For instance, the @samp{fj}
+hierarchy uses @code{iso-2022-jp}.
+
+@vindex gnus-group-charset-alist
+This knowledge is encoded in the @code{gnus-group-charset-alist}
+variable, which is an alist of regexps (use the first item to match full
+group names) and default charsets to be used when reading these groups.
+
+@vindex gnus-newsgroup-ignored-charsets
+In addition, some people do use soi-disant @acronym{MIME}-aware agents that
+aren't. These blithely mark messages as being in @code{iso-8859-1}
+even if they really are in @code{koi-8}. To help here, the
+@code{gnus-newsgroup-ignored-charsets} variable can be used. The
+charsets that are listed here will be ignored. The variable can be
+set on a group-by-group basis using the group parameters (@pxref{Group
+Parameters}). The default value is @code{(unknown-8bit x-unknown)},
+which includes values some agents insist on having in there.
+
+@vindex gnus-group-posting-charset-alist
+When posting, @code{gnus-group-posting-charset-alist} is used to
+determine which charsets should not be encoded using the @acronym{MIME}
+encodings. For instance, some hierarchies discourage using
+quoted-printable header encoding.
+
+This variable is an alist of regexps and permitted unencoded charsets
+for posting. Each element of the alist has the form @code{(}@var{test
+header body-list}@code{)}, where:
+
+@table @var
+@item test
+is either a regular expression matching the newsgroup header or a
+variable to query,
+@item header
+is the charset which may be left unencoded in the header (@code{nil}
+means encode all charsets),
+@item body-list
+is a list of charsets which may be encoded using 8bit content-transfer
+encoding in the body, or one of the special values @code{nil} (always
+encode using quoted-printable) or @code{t} (always use 8bit).
+@end table
+
+@cindex Russian
+@cindex koi8-r
+@cindex koi8-u
+@cindex iso-8859-5
+@cindex coding system aliases
+@cindex preferred charset
+
+@xref{Encoding Customization, , Encoding Customization, emacs-mime,
+The Emacs MIME Manual}, for additional variables that control which
+MIME charsets are used when sending messages.
+
+Other charset tricks that may be useful, although not Gnus-specific:
+
+If there are several @acronym{MIME} charsets that encode the same Emacs
+charset, you can choose what charset to use by saying the following:
+
+@lisp
+(put-charset-property 'cyrillic-iso8859-5
+ 'preferred-coding-system 'koi8-r)
+@end lisp
+
+This means that Russian will be encoded using @code{koi8-r} instead of
+the default @code{iso-8859-5} @acronym{MIME} charset.
+
+If you want to read messages in @code{koi8-u}, you can cheat and say
+
+@lisp
+(define-coding-system-alias 'koi8-u 'koi8-r)
+@end lisp
+
+This will almost do the right thing.
+
+And finally, to read charsets like @code{windows-1251}, you can say
+something like
+
+@lisp
+(codepage-setup 1251)
+(define-coding-system-alias 'windows-1251 'cp1251)
+@end lisp
+
+
+@node Article Commands
+@section Article Commands
+
+@table @kbd
+
+@item A P
+@cindex PostScript
+@cindex printing
+@kindex A P (Summary)
+@vindex gnus-ps-print-hook
+@findex gnus-summary-print-article
+Generate and print a PostScript image of the article buffer
+(@code{gnus-summary-print-article}). @code{gnus-ps-print-hook} will
+be run just before printing the buffer. An alternative way to print
+article is to use Muttprint (@pxref{Saving Articles}).
+
+@item A C
+@vindex gnus-fetch-partial-articles
+@findex gnus-summary-show-complete-article
+If @code{<backend>-fetch-partial-articles} is non-@code{nil}, Gnus will
+fetch partial articles, if the backend it fetches them from supports
+it. Currently only @code{nnimap} does. If you're looking at a
+partial article, and want to see the complete article instead, then
+the @kbd{A C} command (@code{gnus-summary-show-complete-article}) will
+do so.
+
+@end table
+
+
+@node Summary Sorting
+@section Summary Sorting
+@cindex summary sorting
+
+You can have the summary buffer sorted in various ways, even though I
+can't really see why you'd want that.
+
+@table @kbd
+
+@item C-c C-s C-n
+@kindex C-c C-s C-n (Summary)
+@findex gnus-summary-sort-by-number
+Sort by article number (@code{gnus-summary-sort-by-number}).
+
+@item C-c C-s C-m C-n
+@kindex C-c C-s C-n (Summary)
+@findex gnus-summary-sort-by-most-recent-number
+Sort by most recent article number
+(@code{gnus-summary-sort-by-most-recent-number}).
+
+@item C-c C-s C-a
+@kindex C-c C-s C-a (Summary)
+@findex gnus-summary-sort-by-author
+Sort by author (@code{gnus-summary-sort-by-author}).
+
+@item C-c C-s C-t
+@kindex C-c C-s C-t (Summary)
+@findex gnus-summary-sort-by-recipient
+Sort by recipient (@code{gnus-summary-sort-by-recipient}).
+
+@item C-c C-s C-s
+@kindex C-c C-s C-s (Summary)
+@findex gnus-summary-sort-by-subject
+Sort by subject (@code{gnus-summary-sort-by-subject}).
+
+@item C-c C-s C-d
+@kindex C-c C-s C-d (Summary)
+@findex gnus-summary-sort-by-date
+Sort by date (@code{gnus-summary-sort-by-date}).
+
+@item C-c C-s C-m C-d
+@kindex C-c C-s C-m C-d (Summary)
+@findex gnus-summary-sort-by-most-recent-date
+Sort by most recent date (@code{gnus-summary-sort-by-most-recent-date}).
+
+@item C-c C-s C-l
+@kindex C-c C-s C-l (Summary)
+@findex gnus-summary-sort-by-lines
+Sort by lines (@code{gnus-summary-sort-by-lines}).
+
+@item C-c C-s C-c
+@kindex C-c C-s C-c (Summary)
+@findex gnus-summary-sort-by-chars
+Sort by article length (@code{gnus-summary-sort-by-chars}).
+
+@item C-c C-s C-i
+@kindex C-c C-s C-i (Summary)
+@findex gnus-summary-sort-by-score
+Sort by score (@code{gnus-summary-sort-by-score}).
+
+@item C-c C-s C-r
+@kindex C-c C-s C-r (Summary)
+@findex gnus-summary-sort-by-random
+Randomize (@code{gnus-summary-sort-by-random}).
+
+@item C-c C-s C-o
+@kindex C-c C-s C-o (Summary)
+@findex gnus-summary-sort-by-original
+Sort using the default sorting method
+(@code{gnus-summary-sort-by-original}).
+@end table
+
+These functions will work both when you use threading and when you don't
+use threading. In the latter case, all summary lines will be sorted,
+line by line. In the former case, sorting will be done on a
+root-by-root basis, which might not be what you were looking for. To
+toggle whether to use threading, type @kbd{T T} (@pxref{Thread
+Commands}).
+
+If a prefix argument if given, the sort order is reversed.
+
+
+@node Finding the Parent
+@section Finding the Parent
+@cindex parent articles
+@cindex referring articles
+
+@table @kbd
+@item ^
+@kindex ^ (Summary)
+@findex gnus-summary-refer-parent-article
+If you'd like to read the parent of the current article, and it is not
+displayed in the summary buffer, you might still be able to. That is,
+if the current group is fetched by @acronym{NNTP}, the parent hasn't expired
+and the @code{References} in the current article are not mangled, you
+can just press @kbd{^} or @kbd{A r}
+(@code{gnus-summary-refer-parent-article}). If everything goes well,
+you'll get the parent. If the parent is already displayed in the
+summary buffer, point will just move to this article.
+
+If given a positive numerical prefix, fetch that many articles back into
+the ancestry. If given a negative numerical prefix, fetch just that
+ancestor. So if you say @kbd{3 ^}, Gnus will fetch the parent, the
+grandparent and the great-grandparent of the current article. If you say
+@kbd{-3 ^}, Gnus will only fetch the great-grandparent of the current
+article.
+
+@item A R (Summary)
+@findex gnus-summary-refer-references
+@kindex A R (Summary)
+Fetch all articles mentioned in the @code{References} header of the
+article (@code{gnus-summary-refer-references}).
+
+@item A T (Summary)
+@findex gnus-summary-refer-thread
+@kindex A T (Summary)
+Display the full thread where the current article appears
+(@code{gnus-summary-refer-thread}). This command has to fetch all the
+headers in the current group to work, so it usually takes a while. If
+you do it often, you may consider setting @code{gnus-fetch-old-headers}
+to @code{invisible} (@pxref{Filling In Threads}). This won't have any
+visible effects normally, but it'll make this command work a whole lot
+faster. Of course, it'll make group entry somewhat slow.
+
+@vindex gnus-refer-thread-limit
+The @code{gnus-refer-thread-limit} variable says how many old (i.e.,
+articles before the first displayed in the current group) headers to
+fetch when doing this command. The default is 200. If @code{t}, all
+the available headers will be fetched. This variable can be overridden
+by giving the @kbd{A T} command a numerical prefix.
+
+@item M-^ (Summary)
+@findex gnus-summary-refer-article
+@kindex M-^ (Summary)
+@cindex Message-ID
+@cindex fetching by Message-ID
+You can also ask Gnus for an arbitrary article, no matter what group it
+belongs to. @kbd{M-^} (@code{gnus-summary-refer-article}) will ask you
+for a @code{Message-ID}, which is one of those long, hard-to-read
+thingies that look something like @samp{<38o6up$6f2@@hymir.ifi.uio.no>}.
+You have to get it all exactly right. No fuzzy searches, I'm afraid.
+
+Gnus looks for the @code{Message-ID} in the headers that have already
+been fetched, but also tries all the select methods specified by
+@code{gnus-refer-article-method} if it is not found.
+@end table
+
+@vindex gnus-refer-article-method
+If the group you are reading is located on a back end that does not
+support fetching by @code{Message-ID} very well (like @code{nnspool}),
+you can set @code{gnus-refer-article-method} to an @acronym{NNTP} method. It
+would, perhaps, be best if the @acronym{NNTP} server you consult is the one
+updating the spool you are reading from, but that's not really
+necessary.
+
+It can also be a list of select methods, as well as the special symbol
+@code{current}, which means to use the current select method. If it
+is a list, Gnus will try all the methods in the list until it finds a
+match.
+
+Here's an example setting that will first try the current method, and
+then ask Google if that fails:
+
+@lisp
+(setq gnus-refer-article-method
+ '(current
+ (nnweb "google" (nnweb-type google))))
+@end lisp
+
+Most of the mail back ends support fetching by @code{Message-ID}, but
+do not do a particularly excellent job at it. That is, @code{nnmbox},
+@code{nnbabyl}, @code{nnmaildir}, @code{nnml}, are able to locate
+articles from any groups, while @code{nnfolder}, and @code{nnimap} are
+only able to locate articles that have been posted to the current
+group. @code{nnmh} does not support this at all.
+
+Fortunately, the special @code{nnregistry} back end is able to locate
+articles in any groups, regardless of their back end (@pxref{Registry
+Article Refer Method, fetching by @code{Message-ID} using the
+registry}).
+
+@node Alternative Approaches
+@section Alternative Approaches
+
+Different people like to read news using different methods. This being
+Gnus, we offer a small selection of minor modes for the summary buffers.
+
+@menu
+* Pick and Read:: First mark articles and then read them.
+* Binary Groups:: Auto-decode all articles.
+@end menu
+
+
+@node Pick and Read
+@subsection Pick and Read
+@cindex pick and read
+
+Some newsreaders (like @code{nn} and, uhm, @code{Netnews} on VM/CMS) use
+a two-phased reading interface. The user first marks in a summary
+buffer the articles she wants to read. Then she starts reading the
+articles with just an article buffer displayed.
+
+@findex gnus-pick-mode
+@kindex M-x gnus-pick-mode
+Gnus provides a summary buffer minor mode that allows
+this---@code{gnus-pick-mode}. This basically means that a few process
+mark commands become one-keystroke commands to allow easy marking, and
+it provides one additional command for switching to the summary buffer.
+
+Here are the available keystrokes when using pick mode:
+
+@table @kbd
+@item .
+@kindex . (Pick)
+@findex gnus-pick-article-or-thread
+Pick the article or thread on the current line
+(@code{gnus-pick-article-or-thread}). If the variable
+@code{gnus-thread-hide-subtree} is true, then this key selects the
+entire thread when used at the first article of the thread. Otherwise,
+it selects just the article. If given a numerical prefix, go to that
+thread or article and pick it. (The line number is normally displayed
+at the beginning of the summary pick lines.)
+
+@item SPACE
+@kindex SPACE (Pick)
+@findex gnus-pick-next-page
+Scroll the summary buffer up one page (@code{gnus-pick-next-page}). If
+at the end of the buffer, start reading the picked articles.
+
+@item u
+@kindex u (Pick)
+@findex gnus-pick-unmark-article-or-thread.
+Unpick the thread or article
+(@code{gnus-pick-unmark-article-or-thread}). If the variable
+@code{gnus-thread-hide-subtree} is true, then this key unpicks the
+thread if used at the first article of the thread. Otherwise it unpicks
+just the article. You can give this key a numerical prefix to unpick
+the thread or article at that line.
+
+@item RET
+@kindex RET (Pick)
+@findex gnus-pick-start-reading
+@vindex gnus-pick-display-summary
+Start reading the picked articles (@code{gnus-pick-start-reading}). If
+given a prefix, mark all unpicked articles as read first. If
+@code{gnus-pick-display-summary} is non-@code{nil}, the summary buffer
+will still be visible when you are reading.
+
+@end table
+
+All the normal summary mode commands are still available in the
+pick-mode, with the exception of @kbd{u}. However @kbd{!} is available
+which is mapped to the same function
+@code{gnus-summary-tick-article-forward}.
+
+If this sounds like a good idea to you, you could say:
+
+@lisp
+(add-hook 'gnus-summary-mode-hook 'gnus-pick-mode)
+@end lisp
+
+@vindex gnus-pick-mode-hook
+@code{gnus-pick-mode-hook} is run in pick minor mode buffers.
+
+@vindex gnus-mark-unpicked-articles-as-read
+If @code{gnus-mark-unpicked-articles-as-read} is non-@code{nil}, mark
+all unpicked articles as read. The default is @code{nil}.
+
+@vindex gnus-summary-pick-line-format
+The summary line format in pick mode is slightly different from the
+standard format. At the beginning of each line the line number is
+displayed. The pick mode line format is controlled by the
+@code{gnus-summary-pick-line-format} variable (@pxref{Formatting
+Variables}). It accepts the same format specs that
+@code{gnus-summary-line-format} does (@pxref{Summary Buffer Lines}).
+
+
+@node Binary Groups
+@subsection Binary Groups
+@cindex binary groups
+
+@findex gnus-binary-mode
+@kindex M-x gnus-binary-mode
+If you spend much time in binary groups, you may grow tired of hitting
+@kbd{X u}, @kbd{n}, @kbd{RET} all the time. @kbd{M-x gnus-binary-mode}
+is a minor mode for summary buffers that makes all ordinary Gnus article
+selection functions uudecode series of articles and display the result
+instead of just displaying the articles the normal way.
+
+@kindex g (Binary)
+@findex gnus-binary-show-article
+The only way, in fact, to see the actual articles is the @kbd{g}
+command, when you have turned on this mode
+(@code{gnus-binary-show-article}).
+
+@vindex gnus-binary-mode-hook
+@code{gnus-binary-mode-hook} is called in binary minor mode buffers.
+
+
+@node Tree Display
+@section Tree Display
+@cindex trees
+
+@vindex gnus-use-trees
+If you don't like the normal Gnus summary display, you might try setting
+@code{gnus-use-trees} to @code{t}. This will create (by default) an
+additional @dfn{tree buffer}. You can execute all summary mode commands
+in the tree buffer.
+
+There are a few variables to customize the tree display, of course:
+
+@table @code
+@item gnus-tree-mode-hook
+@vindex gnus-tree-mode-hook
+A hook called in all tree mode buffers.
+
+@item gnus-tree-mode-line-format
+@vindex gnus-tree-mode-line-format
+A format string for the mode bar in the tree mode buffers (@pxref{Mode
+Line Formatting}). The default is @samp{Gnus: %%b %S %Z}. For a list
+of valid specs, @pxref{Summary Buffer Mode Line}.
+
+@item gnus-selected-tree-face
+@vindex gnus-selected-tree-face
+Face used for highlighting the selected article in the tree buffer. The
+default is @code{modeline}.
+
+@item gnus-tree-line-format
+@vindex gnus-tree-line-format
+A format string for the tree nodes. The name is a bit of a misnomer,
+though---it doesn't define a line, but just the node. The default value
+is @samp{%(%[%3,3n%]%)}, which displays the first three characters of
+the name of the poster. It is vital that all nodes are of the same
+length, so you @emph{must} use @samp{%4,4n}-like specifiers.
+
+Valid specs are:
+
+@table @samp
+@item n
+The name of the poster.
+@item f
+The @code{From} header.
+@item N
+The number of the article.
+@item [
+The opening bracket.
+@item ]
+The closing bracket.
+@item s
+The subject.
+@end table
+
+@xref{Formatting Variables}.
+
+Variables related to the display are:
+
+@table @code
+@item gnus-tree-brackets
+@vindex gnus-tree-brackets
+This is used for differentiating between ``real'' articles and
+``sparse'' articles. The format is
+@example
+((@var{real-open} . @var{real-close})
+ (@var{sparse-open} . @var{sparse-close})
+ (@var{dummy-open} . @var{dummy-close}))
+@end example
+and the default is @code{((?[ . ?]) (?( . ?)) (?@{ . ?@}) (?< . ?>))}.
+
+@item gnus-tree-parent-child-edges
+@vindex gnus-tree-parent-child-edges
+This is a list that contains the characters used for connecting parent
+nodes to their children. The default is @code{(?- ?\\ ?|)}.
+
+@end table
+
+@item gnus-tree-minimize-window
+@vindex gnus-tree-minimize-window
+If this variable is non-@code{nil}, Gnus will try to keep the tree
+buffer as small as possible to allow more room for the other Gnus
+windows. If this variable is a number, the tree buffer will never be
+higher than that number. The default is @code{t}. Note that if you
+have several windows displayed side-by-side in a frame and the tree
+buffer is one of these, minimizing the tree window will also resize all
+other windows displayed next to it.
+
+You may also wish to add the following hook to keep the window minimized
+at all times:
+
+@lisp
+(add-hook 'gnus-configure-windows-hook
+ 'gnus-tree-perhaps-minimize)
+@end lisp
+
+@item gnus-generate-tree-function
+@vindex gnus-generate-tree-function
+@findex gnus-generate-horizontal-tree
+@findex gnus-generate-vertical-tree
+The function that actually generates the thread tree. Two predefined
+functions are available: @code{gnus-generate-horizontal-tree} and
+@code{gnus-generate-vertical-tree} (which is the default).
+
+@end table
+
+Here's an example from a horizontal tree buffer:
+
+@example
+@{***@}-(***)-[odd]-[Gun]
+ | \[Jan]
+ | \[odd]-[Eri]
+ | \(***)-[Eri]
+ | \[odd]-[Paa]
+ \[Bjo]
+ \[Gun]
+ \[Gun]-[Jor]
+@end example
+
+Here's the same thread displayed in a vertical tree buffer:
+
+@example
+@group
+@{***@}
+ |--------------------------\-----\-----\
+(***) [Bjo] [Gun] [Gun]
+ |--\-----\-----\ |
+[odd] [Jan] [odd] (***) [Jor]
+ | | |--\
+[Gun] [Eri] [Eri] [odd]
+ |
+ [Paa]
+@end group
+@end example
+
+If you're using horizontal trees, it might be nice to display the trees
+side-by-side with the summary buffer. You could add something like the
+following to your @file{~/.gnus.el} file:
+
+@lisp
+(setq gnus-use-trees t
+ gnus-generate-tree-function 'gnus-generate-horizontal-tree
+ gnus-tree-minimize-window nil)
+(gnus-add-configuration
+ '(article
+ (vertical 1.0
+ (horizontal 0.25
+ (summary 0.75 point)
+ (tree 1.0))
+ (article 1.0))))
+@end lisp
+
+@xref{Window Layout}.
+
+
+@node Mail Group Commands
+@section Mail Group Commands
+@cindex mail group commands
+
+Some commands only make sense in mail groups. If these commands are
+invalid in the current group, they will raise a hell and let you know.
+
+All these commands (except the expiry and edit commands) use the
+process/prefix convention (@pxref{Process/Prefix}).
+
+@table @kbd
+
+@item B e
+@kindex B e (Summary)
+@findex gnus-summary-expire-articles
+@cindex expiring mail
+Run all expirable articles in the current group through the expiry
+process (@code{gnus-summary-expire-articles}). That is, delete all
+expirable articles in the group that have been around for a while.
+(@pxref{Expiring Mail}).
+
+@item B C-M-e
+@kindex B C-M-e (Summary)
+@findex gnus-summary-expire-articles-now
+@cindex expiring mail
+Delete all the expirable articles in the group
+(@code{gnus-summary-expire-articles-now}). This means that @strong{all}
+articles eligible for expiry in the current group will
+disappear forever into that big @file{/dev/null} in the sky.
+
+@item B DEL
+@kindex B DEL (Summary)
+@cindex deleting mail
+@findex gnus-summary-delete-article
+@c @icon{gnus-summary-mail-delete}
+Delete the mail article. This is ``delete'' as in ``delete it from your
+disk forever and ever, never to return again.'' Use with caution.
+(@code{gnus-summary-delete-article}).
+
+@item B m
+@kindex B m (Summary)
+@cindex move mail
+@findex gnus-summary-move-article
+@vindex gnus-preserve-marks
+Move the article from one mail group to another
+(@code{gnus-summary-move-article}). Marks will be preserved if
+@code{gnus-preserve-marks} is non-@code{nil} (which is the default).
+
+@item B c
+@kindex B c (Summary)
+@cindex copy mail
+@findex gnus-summary-copy-article
+@c @icon{gnus-summary-mail-copy}
+Copy the article from one group (mail group or not) to a mail group
+(@code{gnus-summary-copy-article}). Marks will be preserved if
+@code{gnus-preserve-marks} is non-@code{nil} (which is the default).
+
+@item B B
+@kindex B B (Summary)
+@cindex crosspost mail
+@findex gnus-summary-crosspost-article
+Crosspost the current article to some other group
+(@code{gnus-summary-crosspost-article}). This will create a new copy of
+the article in the other group, and the Xref headers of the article will
+be properly updated.
+
+@item B i
+@kindex B i (Summary)
+@findex gnus-summary-import-article
+Import an arbitrary file into the current mail newsgroup
+(@code{gnus-summary-import-article}). You will be prompted for a file
+name, a @code{From} header and a @code{Subject} header.
+
+@item B I
+@kindex B I (Summary)
+@findex gnus-summary-create-article
+Create an empty article in the current mail newsgroups
+(@code{gnus-summary-create-article}). You will be prompted for a
+@code{From} header and a @code{Subject} header.
+
+@item B r
+@kindex B r (Summary)
+@findex gnus-summary-respool-article
+@vindex gnus-summary-respool-default-method
+Respool the mail article (@code{gnus-summary-respool-article}).
+@code{gnus-summary-respool-default-method} will be used as the default
+select method when respooling. This variable is @code{nil} by default,
+which means that the current group select method will be used instead.
+Marks will be preserved if @code{gnus-preserve-marks} is non-@code{nil}
+(which is the default).
+
+@item B w
+@itemx e
+@kindex B w (Summary)
+@kindex e (Summary)
+@findex gnus-summary-edit-article
+@kindex C-c C-c (Article)
+@findex gnus-summary-edit-article-done
+Edit the current article (@code{gnus-summary-edit-article}). To finish
+editing and make the changes permanent, type @kbd{C-c C-c}
+(@code{gnus-summary-edit-article-done}). If you give a prefix to the
+@kbd{C-c C-c} command, Gnus won't re-highlight the article.
+
+@item B q
+@kindex B q (Summary)
+@findex gnus-summary-respool-query
+If you want to re-spool an article, you might be curious as to what group
+the article will end up in before you do the re-spooling. This command
+will tell you (@code{gnus-summary-respool-query}).
+
+@item B t
+@kindex B t (Summary)
+@findex gnus-summary-respool-trace
+Similarly, this command will display all fancy splitting patterns used
+when respooling, if any (@code{gnus-summary-respool-trace}).
+
+@item B p
+@kindex B p (Summary)
+@findex gnus-summary-article-posted-p
+Some people have a tendency to send you ``courtesy'' copies when they
+follow up to articles you have posted. These usually have a
+@code{Newsgroups} header in them, but not always. This command
+(@code{gnus-summary-article-posted-p}) will try to fetch the current
+article from your news server (or rather, from
+@code{gnus-refer-article-method} or @code{gnus-select-method}) and will
+report back whether it found the article or not. Even if it says that
+it didn't find the article, it may have been posted anyway---mail
+propagation is much faster than news propagation, and the news copy may
+just not have arrived yet.
+
+@item K E
+@kindex K E (Summary)
+@findex gnus-article-encrypt-body
+@vindex gnus-article-encrypt-protocol
+Encrypt the body of an article (@code{gnus-article-encrypt-body}).
+The body is encrypted with the encryption protocol specified by the
+variable @code{gnus-article-encrypt-protocol}.
+
+@end table
+
+@vindex gnus-move-split-methods
+@cindex moving articles
+If you move (or copy) articles regularly, you might wish to have Gnus
+suggest where to put the articles. @code{gnus-move-split-methods} is a
+variable that uses the same syntax as @code{gnus-split-methods}
+(@pxref{Saving Articles}). You may customize that variable to create
+suggestions you find reasonable. (Note that
+@code{gnus-move-split-methods} uses group names where
+@code{gnus-split-methods} uses file names.)
+
+@lisp
+(setq gnus-move-split-methods
+ '(("^From:.*Lars Magne" "nnml:junk")
+ ("^Subject:.*gnus" "nnfolder:important")
+ (".*" "nnml:misc")))
+@end lisp
+
+
+@node Various Summary Stuff
+@section Various Summary Stuff
+
+@menu
+* Summary Group Information:: Information oriented commands.
+* Searching for Articles:: Multiple article commands.
+* Summary Generation Commands::
+* Really Various Summary Commands:: Those pesky non-conformant commands.
+@end menu
+
+@table @code
+@vindex gnus-summary-display-while-building
+@item gnus-summary-display-while-building
+If non-@code{nil}, show and update the summary buffer as it's being
+built. If @code{t}, update the buffer after every line is inserted.
+If the value is an integer, @var{n}, update the display every @var{n}
+lines. The default is @code{nil}.
+
+@vindex gnus-summary-display-arrow
+@item gnus-summary-display-arrow
+If non-@code{nil}, display an arrow in the fringe to indicate the
+current article.
+
+@vindex gnus-summary-mode-hook
+@item gnus-summary-mode-hook
+This hook is called when creating a summary mode buffer.
+
+@vindex gnus-summary-generate-hook
+@item gnus-summary-generate-hook
+This is called as the last thing before doing the threading and the
+generation of the summary buffer. It's quite convenient for customizing
+the threading variables based on what data the newsgroup has. This hook
+is called from the summary buffer after most summary buffer variables
+have been set.
+
+@vindex gnus-summary-prepare-hook
+@item gnus-summary-prepare-hook
+It is called after the summary buffer has been generated. You might use
+it to, for instance, highlight lines or modify the look of the buffer in
+some other ungodly manner. I don't care.
+
+@vindex gnus-summary-prepared-hook
+@item gnus-summary-prepared-hook
+A hook called as the very last thing after the summary buffer has been
+generated.
+
+@vindex gnus-summary-ignore-duplicates
+@item gnus-summary-ignore-duplicates
+When Gnus discovers two articles that have the same @code{Message-ID},
+it has to do something drastic. No articles are allowed to have the
+same @code{Message-ID}, but this may happen when reading mail from some
+sources. Gnus allows you to customize what happens with this variable.
+If it is @code{nil} (which is the default), Gnus will rename the
+@code{Message-ID} (for display purposes only) and display the article as
+any other article. If this variable is @code{t}, it won't display the
+article---it'll be as if it never existed.
+
+@vindex gnus-alter-articles-to-read-function
+@item gnus-alter-articles-to-read-function
+This function, which takes two parameters (the group name and the list
+of articles to be selected), is called to allow the user to alter the
+list of articles to be selected.
+
+For instance, the following function adds the list of cached articles to
+the list in one particular group:
+
+@lisp
+(defun my-add-cached-articles (group articles)
+ (if (string= group "some.group")
+ (append gnus-newsgroup-cached articles)
+ articles))
+@end lisp
+
+@vindex gnus-newsgroup-variables
+@item gnus-newsgroup-variables
+A list of newsgroup (summary buffer) local variables, or cons of
+variables and their default expressions to be evalled (when the default
+values are not @code{nil}), that should be made global while the summary
+buffer is active.
+
+Note: The default expressions will be evaluated (using function
+@code{eval}) before assignment to the local variable rather than just
+assigned to it. If the default expression is the symbol @code{global},
+that symbol will not be evaluated but the global value of the local
+variable will be used instead.
+
+These variables can be used to set variables in the group parameters
+while still allowing them to affect operations done in other
+buffers. For example:
+
+@lisp
+(setq gnus-newsgroup-variables
+ '(message-use-followup-to
+ (gnus-visible-headers .
+ "^From:\\|^Newsgroups:\\|^Subject:\\|^Date:\\|^To:")))
+@end lisp
+
+Also @pxref{Group Parameters}.
+
+@end table
+
+
+@node Summary Group Information
+@subsection Summary Group Information
+
+@table @kbd
+
+@item H d
+@kindex H d (Summary)
+@findex gnus-summary-describe-group
+Give a brief description of the current group
+(@code{gnus-summary-describe-group}). If given a prefix, force
+rereading the description from the server.
+
+@item H h
+@kindex H h (Summary)
+@findex gnus-summary-describe-briefly
+Give an extremely brief description of the most important summary
+keystrokes (@code{gnus-summary-describe-briefly}).
+
+@item H i
+@kindex H i (Summary)
+@findex gnus-info-find-node
+Go to the Gnus info node (@code{gnus-info-find-node}).
+@end table
+
+
+@node Searching for Articles
+@subsection Searching for Articles
+
+@table @kbd
+
+@item M-s
+@kindex M-s (Summary)
+@findex gnus-summary-search-article-forward
+Search through all subsequent (raw) articles for a regexp
+(@code{gnus-summary-search-article-forward}).
+
+@item M-r
+@kindex M-r (Summary)
+@findex gnus-summary-search-article-backward
+Search through all previous (raw) articles for a regexp
+(@code{gnus-summary-search-article-backward}).
+
+@item M-S
+@kindex M-S (Summary)
+@findex gnus-summary-repeat-search-article-forward
+Repeat the previous search forwards
+(@code{gnus-summary-repeat-search-article-forward}).
+
+@item M-R
+@kindex M-R (Summary)
+@findex gnus-summary-repeat-search-article-backward
+Repeat the previous search backwards
+(@code{gnus-summary-repeat-search-article-backward}).
+
+@item &
+@kindex & (Summary)
+@findex gnus-summary-execute-command
+This command will prompt you for a header, a regular expression to match
+on this field, and a command to be executed if the match is made
+(@code{gnus-summary-execute-command}). If the header is an empty
+string, the match is done on the entire article. If given a prefix,
+search backward instead.
+
+For instance, @kbd{& RET some.*string RET #} will put the process mark on
+all articles that have heads or bodies that match @samp{some.*string}.
+
+@item M-&
+@kindex M-& (Summary)
+@findex gnus-summary-universal-argument
+Perform any operation on all articles that have been marked with
+the process mark (@code{gnus-summary-universal-argument}).
+@end table
+
+@node Summary Generation Commands
+@subsection Summary Generation Commands
+
+@table @kbd
+
+@item Y g
+@kindex Y g (Summary)
+@findex gnus-summary-prepare
+Regenerate the current summary buffer (@code{gnus-summary-prepare}).
+
+@item Y c
+@kindex Y c (Summary)
+@findex gnus-summary-insert-cached-articles
+Pull all cached articles (for the current group) into the summary buffer
+(@code{gnus-summary-insert-cached-articles}).
+
+@item Y d
+@kindex Y d (Summary)
+@findex gnus-summary-insert-dormant-articles
+Pull all dormant articles (for the current group) into the summary buffer
+(@code{gnus-summary-insert-dormant-articles}).
+
+@item Y t
+@kindex Y t (Summary)
+@findex gnus-summary-insert-ticked-articles
+Pull all ticked articles (for the current group) into the summary buffer
+(@code{gnus-summary-insert-ticked-articles}).
+
+@end table
+
+
+@node Really Various Summary Commands
+@subsection Really Various Summary Commands
+
+@table @kbd
+
+@item A D
+@itemx C-d
+@kindex C-d (Summary)
+@kindex A D (Summary)
+@findex gnus-summary-enter-digest-group
+If the current article is a collection of other articles (for instance,
+a digest), you might use this command to enter a group based on the that
+article (@code{gnus-summary-enter-digest-group}). Gnus will try to
+guess what article type is currently displayed unless you give a prefix
+to this command, which forces a ``digest'' interpretation. Basically,
+whenever you see a message that is a collection of other messages of
+some format, you @kbd{C-d} and read these messages in a more convenient
+fashion.
+
+@vindex gnus-auto-select-on-ephemeral-exit
+The variable @code{gnus-auto-select-on-ephemeral-exit} controls what
+article should be selected after exiting a digest group. Valid values
+include:
+
+@table @code
+@item next
+Select the next article.
+
+@item next-unread
+Select the next unread article.
+
+@item next-noselect
+Move the cursor to the next article. This is the default.
+
+@item next-unread-noselect
+Move the cursor to the next unread article.
+@end table
+
+If it has any other value or there is no next (unread) article, the
+article selected before entering to the digest group will appear.
+
+@item C-M-d
+@kindex C-M-d (Summary)
+@findex gnus-summary-read-document
+This command is very similar to the one above, but lets you gather
+several documents into one biiig group
+(@code{gnus-summary-read-document}). It does this by opening several
+@code{nndoc} groups for each document, and then opening an
+@code{nnvirtual} group on top of these @code{nndoc} groups. This
+command understands the process/prefix convention
+(@pxref{Process/Prefix}).
+
+@item C-t
+@kindex C-t (Summary)
+@findex gnus-summary-toggle-truncation
+Toggle truncation of summary lines
+(@code{gnus-summary-toggle-truncation}). This will probably confuse the
+line centering function in the summary buffer, so it's not a good idea
+to have truncation switched off while reading articles.
+
+@item =
+@kindex = (Summary)
+@findex gnus-summary-expand-window
+Expand the summary buffer window (@code{gnus-summary-expand-window}).
+If given a prefix, force an @code{article} window configuration.
+
+@item C-M-e
+@kindex C-M-e (Summary)
+@findex gnus-summary-edit-parameters
+Edit the group parameters (@pxref{Group Parameters}) of the current
+group (@code{gnus-summary-edit-parameters}).
+
+@item C-M-a
+@kindex C-M-a (Summary)
+@findex gnus-summary-customize-parameters
+Customize the group parameters (@pxref{Group Parameters}) of the current
+group (@code{gnus-summary-customize-parameters}).
+
+@end table
+
+
+@node Exiting the Summary Buffer
+@section Exiting the Summary Buffer
+@cindex summary exit
+@cindex exiting groups
+
+Exiting from the summary buffer will normally update all info on the
+group and return you to the group buffer.
+
+@table @kbd
+
+@item Z Z
+@itemx Z Q
+@itemx q
+@kindex Z Z (Summary)
+@kindex Z Q (Summary)
+@kindex q (Summary)
+@findex gnus-summary-exit
+@vindex gnus-summary-exit-hook
+@vindex gnus-summary-prepare-exit-hook
+@vindex gnus-group-no-more-groups-hook
+@c @icon{gnus-summary-exit}
+Exit the current group and update all information on the group
+(@code{gnus-summary-exit}). @code{gnus-summary-prepare-exit-hook} is
+called before doing much of the exiting, which calls
+@code{gnus-summary-expire-articles} by default.
+@code{gnus-summary-exit-hook} is called after finishing the exit
+process. @code{gnus-group-no-more-groups-hook} is run when returning to
+group mode having no more (unread) groups.
+
+@item Z E
+@itemx Q
+@kindex Z E (Summary)
+@kindex Q (Summary)
+@findex gnus-summary-exit-no-update
+Exit the current group without updating any information on the group
+(@code{gnus-summary-exit-no-update}).
+
+@item Z c
+@itemx c
+@kindex Z c (Summary)
+@kindex c (Summary)
+@findex gnus-summary-catchup-and-exit
+@c @icon{gnus-summary-catchup-and-exit}
+Mark all unticked articles in the group as read and then exit
+(@code{gnus-summary-catchup-and-exit}).
+
+@item Z C
+@kindex Z C (Summary)
+@findex gnus-summary-catchup-all-and-exit
+Mark all articles, even the ticked ones, as read and then exit
+(@code{gnus-summary-catchup-all-and-exit}).
+
+@item Z n
+@kindex Z n (Summary)
+@findex gnus-summary-catchup-and-goto-next-group
+Mark all articles as read and go to the next group
+(@code{gnus-summary-catchup-and-goto-next-group}).
+
+@item Z p
+@kindex Z p (Summary)
+@findex gnus-summary-catchup-and-goto-prev-group
+Mark all articles as read and go to the previous group
+(@code{gnus-summary-catchup-and-goto-prev-group}).
+
+@item Z R
+@itemx C-x C-s
+@kindex Z R (Summary)
+@kindex C-x C-s (Summary)
+@findex gnus-summary-reselect-current-group
+Exit this group, and then enter it again
+(@code{gnus-summary-reselect-current-group}). If given a prefix, select
+all articles, both read and unread.
+
+@item Z G
+@itemx M-g
+@kindex Z G (Summary)
+@kindex M-g (Summary)
+@findex gnus-summary-rescan-group
+@c @icon{gnus-summary-mail-get}
+Exit the group, check for new articles in the group, and select the
+group (@code{gnus-summary-rescan-group}). If given a prefix, select all
+articles, both read and unread.
+
+@item Z N
+@kindex Z N (Summary)
+@findex gnus-summary-next-group
+Exit the group and go to the next group
+(@code{gnus-summary-next-group}).
+
+@item Z P
+@kindex Z P (Summary)
+@findex gnus-summary-prev-group
+Exit the group and go to the previous group
+(@code{gnus-summary-prev-group}).
+
+@item Z s
+@kindex Z s (Summary)
+@findex gnus-summary-save-newsrc
+Save the current number of read/marked articles in the dribble buffer
+and then save the dribble buffer (@code{gnus-summary-save-newsrc}). If
+given a prefix, also save the @file{.newsrc} file(s). Using this
+command will make exit without updating (the @kbd{Q} command) worthless.
+@end table
+
+@vindex gnus-exit-group-hook
+@code{gnus-exit-group-hook} is called when you exit the current group
+with an ``updating'' exit. For instance @kbd{Q}
+(@code{gnus-summary-exit-no-update}) does not call this hook.
+
+@findex gnus-summary-wake-up-the-dead
+@findex gnus-dead-summary-mode
+@vindex gnus-kill-summary-on-exit
+If you're in the habit of exiting groups, and then changing your mind
+about it, you might set @code{gnus-kill-summary-on-exit} to @code{nil}.
+If you do that, Gnus won't kill the summary buffer when you exit it.
+(Quelle surprise!) Instead it will change the name of the buffer to
+something like @file{*Dead Summary ... *} and install a minor mode
+called @code{gnus-dead-summary-mode}. Now, if you switch back to this
+buffer, you'll find that all keys are mapped to a function called
+@code{gnus-summary-wake-up-the-dead}. So tapping any keys in a dead
+summary buffer will result in a live, normal summary buffer.
+
+There will never be more than one dead summary buffer at any one time.
+
+@vindex gnus-use-cross-reference
+The data on the current group will be updated (which articles you have
+read, which articles you have replied to, etc.)@: when you exit the
+summary buffer. If the @code{gnus-use-cross-reference} variable is
+@code{t} (which is the default), articles that are cross-referenced to
+this group and are marked as read, will also be marked as read in the
+other subscribed groups they were cross-posted to. If this variable is
+neither @code{nil} nor @code{t}, the article will be marked as read in
+both subscribed and unsubscribed groups (@pxref{Crosspost Handling}).
+
+
+@node Crosspost Handling
+@section Crosspost Handling
+
+@cindex velveeta
+@cindex spamming
+Marking cross-posted articles as read ensures that you'll never have to
+read the same article more than once. Unless, of course, somebody has
+posted it to several groups separately. Posting the same article to
+several groups (not cross-posting) is called @dfn{spamming}, and you are
+by law required to send nasty-grams to anyone who perpetrates such a
+heinous crime.
+
+Remember: Cross-posting is kinda ok, but posting the same article
+separately to several groups is not. Massive cross-posting (aka.
+@dfn{velveeta}) is to be avoided at all costs, and you can even use the
+@code{gnus-summary-mail-crosspost-complaint} command to complain about
+excessive crossposting (@pxref{Summary Mail Commands}).
+
+@cindex cross-posting
+@cindex Xref
+@cindex @acronym{NOV}
+One thing that may cause Gnus to not do the cross-posting thing
+correctly is if you use an @acronym{NNTP} server that supports @sc{xover}
+(which is very nice, because it speeds things up considerably) which
+does not include the @code{Xref} header in its @acronym{NOV} lines. This is
+Evil, but all too common, alas, alack. Gnus tries to Do The Right Thing
+even with @sc{xover} by registering the @code{Xref} lines of all
+articles you actually read, but if you kill the articles, or just mark
+them as read without reading them, Gnus will not get a chance to snoop
+the @code{Xref} lines out of these articles, and will be unable to use
+the cross reference mechanism.
+
+@cindex LIST overview.fmt
+@cindex overview.fmt
+To check whether your @acronym{NNTP} server includes the @code{Xref} header
+in its overview files, try @samp{telnet your.nntp.server nntp},
+@samp{MODE READER} on @code{inn} servers, and then say @samp{LIST
+overview.fmt}. This may not work, but if it does, and the last line you
+get does not read @samp{Xref:full}, then you should shout and whine at
+your news admin until she includes the @code{Xref} header in the
+overview files.
+
+If you want Gnus to get the @code{Xref}s right all the time, you have to
+set @code{nntp-nov-is-evil} to @code{t}, which slows things down
+considerably. Also @pxref{Slow/Expensive Connection}.
+
+C'est la vie.
+
+For an alternative approach, @pxref{Duplicate Suppression}.
+
+
+@node Duplicate Suppression
+@section Duplicate Suppression
+
+By default, Gnus tries to make sure that you don't have to read the same
+article more than once by utilizing the crossposting mechanism
+(@pxref{Crosspost Handling}). However, that simple and efficient
+approach may not work satisfactory for some users for various
+reasons.
+
+@enumerate
+@item
+The @acronym{NNTP} server may fail to generate the @code{Xref} header. This
+is evil and not very common.
+
+@item
+The @acronym{NNTP} server may fail to include the @code{Xref} header in the
+@file{.overview} data bases. This is evil and all too common, alas.
+
+@item
+You may be reading the same group (or several related groups) from
+different @acronym{NNTP} servers.
+
+@item
+You may be getting mail that duplicates articles posted to groups.
+@end enumerate
+
+I'm sure there are other situations where @code{Xref} handling fails as
+well, but these four are the most common situations.
+
+If, and only if, @code{Xref} handling fails for you, then you may
+consider switching on @dfn{duplicate suppression}. If you do so, Gnus
+will remember the @code{Message-ID}s of all articles you have read or
+otherwise marked as read, and then, as if by magic, mark them as read
+all subsequent times you see them---in @emph{all} groups. Using this
+mechanism is quite likely to be somewhat inefficient, but not overly
+so. It's certainly preferable to reading the same articles more than
+once.
+
+Duplicate suppression is not a very subtle instrument. It's more like a
+sledge hammer than anything else. It works in a very simple
+fashion---if you have marked an article as read, it adds this Message-ID
+to a cache. The next time it sees this Message-ID, it will mark the
+article as read with the @samp{M} mark. It doesn't care what group it
+saw the article in.
+
+@table @code
+@item gnus-suppress-duplicates
+@vindex gnus-suppress-duplicates
+If non-@code{nil}, suppress duplicates.
+
+@item gnus-save-duplicate-list
+@vindex gnus-save-duplicate-list
+If non-@code{nil}, save the list of duplicates to a file. This will
+make startup and shutdown take longer, so the default is @code{nil}.
+However, this means that only duplicate articles read in a single Gnus
+session are suppressed.
+
+@item gnus-duplicate-list-length
+@vindex gnus-duplicate-list-length
+This variable says how many @code{Message-ID}s to keep in the duplicate
+suppression list. The default is 10000.
+
+@item gnus-duplicate-file
+@vindex gnus-duplicate-file
+The name of the file to store the duplicate suppression list in. The
+default is @file{~/News/suppression}.
+@end table
+
+If you have a tendency to stop and start Gnus often, setting
+@code{gnus-save-duplicate-list} to @code{t} is probably a good idea. If
+you leave Gnus running for weeks on end, you may have it @code{nil}. On
+the other hand, saving the list makes startup and shutdown much slower,
+so that means that if you stop and start Gnus often, you should set
+@code{gnus-save-duplicate-list} to @code{nil}. Uhm. I'll leave this up
+to you to figure out, I think.
+
+@node Security
+@section Security
+
+Gnus is able to verify signed messages or decrypt encrypted messages.
+The formats that are supported are @acronym{PGP}, @acronym{PGP/MIME}
+and @acronym{S/MIME}, however you need some external programs to get
+things to work:
+
+@enumerate
+@item
+To handle @acronym{PGP} and @acronym{PGP/MIME} messages, you have to
+install an OpenPGP implementation such as GnuPG@. The Lisp interface
+to GnuPG included with Emacs is called EasyPG (@pxref{Top, ,EasyPG,
+epa, EasyPG Assistant user's manual}), but PGG (@pxref{Top, ,PGG, pgg,
+PGG Manual}), and Mailcrypt are also supported.
+
+@item
+To handle @acronym{S/MIME} message, you need to install OpenSSL@. OpenSSL 0.9.6
+or newer is recommended.
+
+@end enumerate
+
+The variables that control security functionality on reading/composing
+messages include:
+
+@table @code
+@item mm-verify-option
+@vindex mm-verify-option
+Option of verifying signed parts. @code{never}, not verify;
+@code{always}, always verify; @code{known}, only verify known
+protocols. Otherwise, ask user.
+
+@item mm-decrypt-option
+@vindex mm-decrypt-option
+Option of decrypting encrypted parts. @code{never}, no decryption;
+@code{always}, always decrypt; @code{known}, only decrypt known
+protocols. Otherwise, ask user.
+
+@item mm-sign-option
+@vindex mm-sign-option
+Option of creating signed parts. @code{nil}, use default signing
+keys; @code{guided}, ask user to select signing keys from the menu.
+
+@item mm-encrypt-option
+@vindex mm-encrypt-option
+Option of creating encrypted parts. @code{nil}, use the first
+public-key matching the @samp{From:} header as the recipient;
+@code{guided}, ask user to select recipient keys from the menu.
+
+@item mml1991-use
+@vindex mml1991-use
+Symbol indicating elisp interface to OpenPGP implementation for
+@acronym{PGP} messages. The default is @code{epg}, but @code{pgg},
+and @code{mailcrypt} are also supported although
+deprecated. By default, Gnus uses the first available interface in
+this order.
+
+@item mml2015-use
+@vindex mml2015-use
+Symbol indicating elisp interface to OpenPGP implementation for
+@acronym{PGP/MIME} messages. The default is @code{epg}, but
+@code{pgg}, and @code{mailcrypt} are also supported
+although deprecated. By default, Gnus uses the first available
+interface in this order.
+
+@end table
+
+By default the buttons that display security information are not
+shown, because they clutter reading the actual e-mail. You can type
+@kbd{K b} manually to display the information. Use the
+@code{gnus-buttonized-mime-types} and
+@code{gnus-unbuttonized-mime-types} variables to control this
+permanently. @ref{MIME Commands} for further details, and hints on
+how to customize these variables to always display security
+information.
+
+@cindex snarfing keys
+@cindex importing PGP keys
+@cindex PGP key ring import
+Snarfing OpenPGP keys (i.e., importing keys from articles into your
+key ring) is not supported explicitly through a menu item or command,
+rather Gnus do detect and label keys as @samp{application/pgp-keys},
+allowing you to specify whatever action you think is appropriate
+through the usual @acronym{MIME} infrastructure. You can use a
+@file{~/.mailcap} entry (@pxref{mailcap, , mailcap, emacs-mime, The
+Emacs MIME Manual}) such as the following to import keys using GNU
+Privacy Guard when you click on the @acronym{MIME} button
+(@pxref{Using MIME}).
+
+@example
+application/pgp-keys; gpg --import --interactive --verbose; needsterminal
+@end example
+@noindent
+This happens to also be the default action defined in
+@code{mailcap-mime-data}.
+
+More information on how to set things for sending outgoing signed and
+encrypted messages up can be found in the message manual
+(@pxref{Security, ,Security, message, Message Manual}).
+
+@node Mailing List
+@section Mailing List
+@cindex mailing list
+@cindex RFC 2396
+
+@kindex A M (summary)
+@findex gnus-mailing-list-insinuate
+Gnus understands some mailing list fields of RFC 2369. To enable it,
+add a @code{to-list} group parameter (@pxref{Group Parameters}),
+possibly using @kbd{A M} (@code{gnus-mailing-list-insinuate}) in the
+summary buffer.
+
+That enables the following commands to the summary buffer:
+
+@table @kbd
+
+@item C-c C-n h
+@kindex C-c C-n h (Summary)
+@findex gnus-mailing-list-help
+Send a message to fetch mailing list help, if List-Help field exists.
+
+@item C-c C-n s
+@kindex C-c C-n s (Summary)
+@findex gnus-mailing-list-subscribe
+Send a message to subscribe the mailing list, if List-Subscribe field exists.
+
+@item C-c C-n u
+@kindex C-c C-n u (Summary)
+@findex gnus-mailing-list-unsubscribe
+Send a message to unsubscribe the mailing list, if List-Unsubscribe
+field exists.
+
+@item C-c C-n p
+@kindex C-c C-n p (Summary)
+@findex gnus-mailing-list-post
+Post to the mailing list, if List-Post field exists.
+
+@item C-c C-n o
+@kindex C-c C-n o (Summary)
+@findex gnus-mailing-list-owner
+Send a message to the mailing list owner, if List-Owner field exists.
+
+@item C-c C-n a
+@kindex C-c C-n a (Summary)
+@findex gnus-mailing-list-archive
+Browse the mailing list archive, if List-Archive field exists.
+
+@end table
+
+
+@node Article Buffer
+@chapter Article Buffer
+@cindex article buffer
+
+The articles are displayed in the article buffer, of which there is only
+one. All the summary buffers share the same article buffer unless you
+tell Gnus otherwise.
+
+@menu
+* Hiding Headers:: Deciding what headers should be displayed.
+* Using MIME:: Pushing articles through @acronym{MIME} before reading them.
+* HTML:: Reading @acronym{HTML} messages.
+* Customizing Articles:: Tailoring the look of the articles.
+* Article Keymap:: Keystrokes available in the article buffer.
+* Misc Article:: Other stuff.
+@end menu
+
+
+@node Hiding Headers
+@section Hiding Headers
+@cindex hiding headers
+@cindex deleting headers
+
+The top section of each article is the @dfn{head}. (The rest is the
+@dfn{body}, but you may have guessed that already.)
+
+@vindex gnus-show-all-headers
+There is a lot of useful information in the head: the name of the person
+who wrote the article, the date it was written and the subject of the
+article. That's well and nice, but there's also lots of information
+most people do not want to see---what systems the article has passed
+through before reaching you, the @code{Message-ID}, the
+@code{References}, etc.@: ad nauseam---and you'll probably want to get rid
+of some of those lines. If you want to keep all those lines in the
+article buffer, you can set @code{gnus-show-all-headers} to @code{t}.
+
+Gnus provides you with two variables for sifting headers:
+
+@table @code
+
+@item gnus-visible-headers
+@vindex gnus-visible-headers
+If this variable is non-@code{nil}, it should be a regular expression
+that says what headers you wish to keep in the article buffer. All
+headers that do not match this variable will be hidden.
+
+For instance, if you only want to see the name of the person who wrote
+the article and the subject, you'd say:
+
+@lisp
+(setq gnus-visible-headers "^From:\\|^Subject:")
+@end lisp
+
+This variable can also be a list of regexps to match headers to
+remain visible.
+
+@item gnus-ignored-headers
+@vindex gnus-ignored-headers
+This variable is the reverse of @code{gnus-visible-headers}. If this
+variable is set (and @code{gnus-visible-headers} is @code{nil}), it
+should be a regular expression that matches all lines that you want to
+hide. All lines that do not match this variable will remain visible.
+
+For instance, if you just want to get rid of the @code{References} line
+and the @code{Xref} line, you might say:
+
+@lisp
+(setq gnus-ignored-headers "^References:\\|^Xref:")
+@end lisp
+
+This variable can also be a list of regexps to match headers to
+be removed.
+
+Note that if @code{gnus-visible-headers} is non-@code{nil}, this
+variable will have no effect.
+
+@end table
+
+@vindex gnus-sorted-header-list
+Gnus can also sort the headers for you. (It does this by default.) You
+can control the sorting by setting the @code{gnus-sorted-header-list}
+variable. It is a list of regular expressions that says in what order
+the headers are to be displayed.
+
+For instance, if you want the name of the author of the article first,
+and then the subject, you might say something like:
+
+@lisp
+(setq gnus-sorted-header-list '("^From:" "^Subject:"))
+@end lisp
+
+Any headers that are to remain visible, but are not listed in this
+variable, will be displayed in random order after all the headers listed in this variable.
+
+@findex gnus-article-hide-boring-headers
+@vindex gnus-boring-article-headers
+You can hide further boring headers by setting
+@code{gnus-treat-hide-boring-headers} to @code{head}. What this function
+does depends on the @code{gnus-boring-article-headers} variable. It's a
+list, but this list doesn't actually contain header names. Instead it
+lists various @dfn{boring conditions} that Gnus can check and remove
+from sight.
+
+These conditions are:
+@table @code
+@item empty
+Remove all empty headers.
+@item followup-to
+Remove the @code{Followup-To} header if it is identical to the
+@code{Newsgroups} header.
+@item reply-to
+Remove the @code{Reply-To} header if it lists the same addresses as
+the @code{From} header, or if the @code{broken-reply-to} group
+parameter is set.
+@item newsgroups
+Remove the @code{Newsgroups} header if it only contains the current group
+name.
+@item to-address
+Remove the @code{To} header if it only contains the address identical to
+the current group's @code{to-address} parameter.
+@item to-list
+Remove the @code{To} header if it only contains the address identical to
+the current group's @code{to-list} parameter.
+@item cc-list
+Remove the @code{Cc} header if it only contains the address identical to
+the current group's @code{to-list} parameter.
+@item date
+Remove the @code{Date} header if the article is less than three days
+old.
+@item long-to
+Remove the @code{To} and/or @code{Cc} header if it is very long.
+@item many-to
+Remove all @code{To} and/or @code{Cc} headers if there are more than one.
+@end table
+
+To include these three elements, you could say something like:
+
+@lisp
+(setq gnus-boring-article-headers
+ '(empty followup-to reply-to))
+@end lisp
+
+This is also the default value for this variable.
+
+
+@node Using MIME
+@section Using MIME
+@cindex @acronym{MIME}
+
+Mime is a standard for waving your hands through the air, aimlessly,
+while people stand around yawning.
+
+@acronym{MIME}, however, is a standard for encoding your articles, aimlessly,
+while all newsreaders die of fear.
+
+@acronym{MIME} may specify what character set the article uses, the encoding
+of the characters, and it also makes it possible to embed pictures and
+other naughty stuff in innocent-looking articles.
+
+@vindex gnus-display-mime-function
+@findex gnus-display-mime
+Gnus pushes @acronym{MIME} articles through @code{gnus-display-mime-function}
+to display the @acronym{MIME} parts. This is @code{gnus-display-mime} by
+default, which creates a bundle of clickable buttons that can be used to
+display, save and manipulate the @acronym{MIME} objects.
+
+The following commands are available when you have placed point over a
+@acronym{MIME} button:
+
+@table @kbd
+@findex gnus-article-press-button
+@item RET (Article)
+@kindex RET (Article)
+@itemx BUTTON-2 (Article)
+Toggle displaying of the @acronym{MIME} object
+(@code{gnus-article-press-button}). If built-in viewers can not display
+the object, Gnus resorts to external viewers in the @file{mailcap}
+files. If a viewer has the @samp{copiousoutput} specification, the
+object is displayed inline.
+
+@findex gnus-mime-view-part
+@item M-RET (Article)
+@kindex M-RET (Article)
+@itemx v (Article)
+Prompt for a method, and then view the @acronym{MIME} object using this
+method (@code{gnus-mime-view-part}).
+
+@findex gnus-mime-view-part-as-type
+@item t (Article)
+@kindex t (Article)
+View the @acronym{MIME} object as if it were a different @acronym{MIME} media type
+(@code{gnus-mime-view-part-as-type}).
+
+@findex gnus-mime-view-part-as-charset
+@item C (Article)
+@kindex C (Article)
+Prompt for a charset, and then view the @acronym{MIME} object using this
+charset (@code{gnus-mime-view-part-as-charset}).
+
+@findex gnus-mime-save-part
+@item o (Article)
+@kindex o (Article)
+Prompt for a file name, and then save the @acronym{MIME} object
+(@code{gnus-mime-save-part}).
+
+@findex gnus-mime-save-part-and-strip
+@item C-o (Article)
+@kindex C-o (Article)
+Prompt for a file name, then save the @acronym{MIME} object and strip it from
+the article. Then proceed to article editing, where a reasonable
+suggestion is being made on how the altered article should look
+like. The stripped @acronym{MIME} object will be referred via the
+message/external-body @acronym{MIME} type.
+(@code{gnus-mime-save-part-and-strip}).
+
+@findex gnus-mime-replace-part
+@item r (Article)
+@kindex r (Article)
+Prompt for a file name, replace the @acronym{MIME} object with an
+external body referring to the file via the message/external-body
+@acronym{MIME} type. (@code{gnus-mime-replace-part}).
+
+@findex gnus-mime-delete-part
+@item d (Article)
+@kindex d (Article)
+Delete the @acronym{MIME} object from the article and replace it with some
+information about the removed @acronym{MIME} object
+(@code{gnus-mime-delete-part}).
+
+@c FIXME: gnus-auto-select-part should be documented here
+
+@findex gnus-mime-copy-part
+@item c (Article)
+@kindex c (Article)
+Copy the @acronym{MIME} object to a fresh buffer and display this buffer
+(@code{gnus-mime-copy-part}). If given a prefix, copy the raw contents
+without decoding. If given a numerical prefix, you can do semi-manual
+charset stuff (see @code{gnus-summary-show-article-charset-alist} in
+@ref{Paging the Article}). Compressed files like @file{.gz} and
+@file{.bz2} are automatically decompressed if
+@code{auto-compression-mode} is enabled (@pxref{Compressed Files,,
+Accessing Compressed Files, emacs, The Emacs Editor}).
+
+@findex gnus-mime-print-part
+@item p (Article)
+@kindex p (Article)
+Print the @acronym{MIME} object (@code{gnus-mime-print-part}). This
+command respects the @samp{print=} specifications in the
+@file{.mailcap} file.
+
+@findex gnus-mime-inline-part
+@item i (Article)
+@kindex i (Article)
+Insert the contents of the @acronym{MIME} object into the buffer
+(@code{gnus-mime-inline-part}) as @samp{text/plain}. If given a prefix, insert
+the raw contents without decoding. If given a numerical prefix, you can
+do semi-manual charset stuff (see
+@code{gnus-summary-show-article-charset-alist} in @ref{Paging the
+Article}). Compressed files like @file{.gz} and @file{.bz2} are
+automatically decompressed depending on @code{jka-compr} regardless of
+@code{auto-compression-mode} (@pxref{Compressed Files,, Accessing
+Compressed Files, emacs, The Emacs Editor}).
+
+@findex gnus-mime-view-part-internally
+@item E (Article)
+@kindex E (Article)
+View the @acronym{MIME} object with an internal viewer. If no internal
+viewer is available, use an external viewer
+(@code{gnus-mime-view-part-internally}).
+
+@findex gnus-mime-view-part-externally
+@item e (Article)
+@kindex e (Article)
+View the @acronym{MIME} object with an external viewer.
+(@code{gnus-mime-view-part-externally}).
+
+@findex gnus-mime-pipe-part
+@item | (Article)
+@kindex | (Article)
+Output the @acronym{MIME} object to a process (@code{gnus-mime-pipe-part}).
+
+@findex gnus-mime-action-on-part
+@item . (Article)
+@kindex . (Article)
+Interactively run an action on the @acronym{MIME} object
+(@code{gnus-mime-action-on-part}).
+
+@end table
+
+Gnus will display some @acronym{MIME} objects automatically. The way Gnus
+determines which parts to do this with is described in the Emacs
+@acronym{MIME} manual.
+
+It might be best to just use the toggling functions from the article
+buffer to avoid getting nasty surprises. (For instance, you enter the
+group @samp{alt.sing-a-long} and, before you know it, @acronym{MIME} has
+decoded the sound file in the article and some horrible sing-a-long song
+comes screaming out your speakers, and you can't find the volume button,
+because there isn't one, and people are starting to look at you, and you
+try to stop the program, but you can't, and you can't find the program
+to control the volume, and everybody else in the room suddenly decides
+to look at you disdainfully, and you'll feel rather stupid.)
+
+Any similarity to real events and people is purely coincidental. Ahem.
+
+Also @pxref{MIME Commands}.
+
+
+@node HTML
+@section @acronym{HTML}
+@cindex @acronym{HTML}
+
+Gnus can display @acronym{HTML} articles nicely formatted in the
+article buffer. There are many methods for doing that, but two of
+them are kind of default methods.
+
+If your Emacs copy has been built with libxml2 support, then Gnus uses
+Emacs' built-in, plain elisp Simple HTML Renderer @code{shr}
+@footnote{@code{shr} displays colors as declared in the @acronym{HTML}
+article but tries to adjust them in order to be readable. If you
+prefer more contrast, @xref{FAQ 4-16}.} which is also used by Emacs'
+browser EWW (@pxref{EWW, ,EWW, emacs, The Emacs Manual}).
+
+If your Emacs copy lacks libxml2 support but you have @code{w3m}
+installed on your system, Gnus uses that to render @acronym{HTML} mail
+and display the results in the article buffer (@code{gnus-w3m}).
+
+For a complete overview, consult @xref{Display Customization, ,Display
+Customization, emacs-mime, The Emacs MIME Manual}. This section only
+describes the default method.
+
+@table @code
+@item mm-text-html-renderer
+@vindex mm-text-html-renderer
+If set to @code{shr}, Gnus uses its own simple @acronym{HTML}
+renderer. If set to @code{gnus-w3m}, it uses @code{w3m}.
+
+@item gnus-blocked-images
+@vindex gnus-blocked-images
+External images that have @acronym{URL}s that match this regexp won't
+be fetched and displayed. For instance, do block all @acronym{URL}s
+that have the string ``ads'' in them, do the following:
+
+@lisp
+(setq gnus-blocked-images "ads")
+@end lisp
+
+This can also be a function to be evaluated. If so, it will be
+called with the group name as the parameter. The default value is
+@code{gnus-block-private-groups}, which will return @samp{"."} for
+anything that isn't a newsgroup. This means that no external images
+will be fetched as a result of reading mail, so that nobody can use
+web bugs (and the like) to track whether you've read email.
+
+Also @pxref{Misc Article} for @code{gnus-inhibit-images}.
+
+@item gnus-html-cache-directory
+@vindex gnus-html-cache-directory
+Gnus will download and cache images according to how
+@code{gnus-blocked-images} is set. These images will be stored in
+this directory.
+
+@item gnus-html-cache-size
+@vindex gnus-html-cache-size
+When @code{gnus-html-cache-size} bytes have been used in that
+directory, the oldest files will be deleted. The default is 500MB.
+
+@item gnus-html-frame-width
+@vindex gnus-html-frame-width
+The width to use when rendering HTML@. The default is 70.
+
+@item gnus-max-image-proportion
+@vindex gnus-max-image-proportion
+How big pictures displayed are in relation to the window they're in.
+A value of 0.7 (the default) means that they are allowed to take up
+70% of the width and height of the window. If they are larger than
+this, and Emacs supports it, then the images will be rescaled down to
+fit these criteria.
+
+@end table
+
+To use this, make sure that you have @code{w3m} and @code{curl}
+installed. If you have, then Gnus should display @acronym{HTML}
+automatically.
+
+
+
+@node Customizing Articles
+@section Customizing Articles
+@cindex article customization
+
+A slew of functions for customizing how the articles are to look like
+exist. You can call these functions interactively
+(@pxref{Article Washing}), or you can have them
+called automatically when you select the articles.
+
+To have them called automatically, you should set the corresponding
+``treatment'' variable. For instance, to have headers hidden, you'd set
+@code{gnus-treat-hide-headers}. Below is a list of variables that can
+be set, but first we discuss the values these variables can have.
+
+Note: Some values, while valid, make little sense. Check the list below
+for sensible values.
+
+@enumerate
+@item
+@code{nil}: Don't do this treatment.
+
+@item
+@code{t}: Do this treatment on all body parts.
+
+@item
+@code{head}: Do the treatment on the headers.
+
+@item
+@code{first}: Do this treatment on the first body part.
+
+@item
+@code{last}: Do this treatment on the last body part.
+
+@item
+An integer: Do this treatment on all body parts that have a length less
+than this number.
+
+@item
+A list of strings: Do this treatment on all body parts that are in
+articles that are read in groups that have names that match one of the
+regexps in the list.
+
+@item
+A list where the first element is not a string:
+
+The list is evaluated recursively. The first element of the list is a
+predicate. The following predicates are recognized: @code{or},
+@code{and}, @code{not} and @code{typep}. Here's an example:
+
+@lisp
+(or last
+ (typep "text/x-vcard"))
+@end lisp
+
+@item
+A function: the function is called with no arguments and should return
+@code{nil} or non-@code{nil}. The current article is available in the
+buffer named by @code{gnus-article-buffer}.
+
+@end enumerate
+
+You may have noticed that the word @dfn{part} is used here. This refers
+to the fact that some messages are @acronym{MIME} multipart articles that may
+be divided into several parts. Articles that are not multiparts are
+considered to contain just a single part.
+
+@vindex gnus-article-treat-types
+Are the treatments applied to all sorts of multipart parts? Yes, if you
+want to, but by default, only @samp{text/plain} parts are given the
+treatment. This is controlled by the @code{gnus-article-treat-types}
+variable, which is a list of regular expressions that are matched to the
+type of the part. This variable is ignored if the value of the
+controlling variable is a predicate list, as described above.
+
+@ifinfo
+@c Avoid sort of redundant entries in the same section for the printed
+@c manual, but add them in info to allow 'i gnus-treat-foo-bar RET' or
+@c 'i foo-bar'.
+@vindex gnus-treat-buttonize
+@vindex gnus-treat-buttonize-head
+@vindex gnus-treat-capitalize-sentences
+@vindex gnus-treat-overstrike
+@vindex gnus-treat-strip-cr
+@vindex gnus-treat-strip-headers-in-body
+@vindex gnus-treat-strip-leading-blank-lines
+@vindex gnus-treat-strip-multiple-blank-lines
+@vindex gnus-treat-strip-pem
+@vindex gnus-treat-strip-trailing-blank-lines
+@vindex gnus-treat-unsplit-urls
+@vindex gnus-treat-wash-html
+@vindex gnus-treat-date
+@vindex gnus-treat-from-picon
+@vindex gnus-treat-mail-picon
+@vindex gnus-treat-newsgroups-picon
+@vindex gnus-treat-from-gravatar
+@vindex gnus-treat-mail-gravatar
+@vindex gnus-treat-display-smileys
+@vindex gnus-treat-body-boundary
+@vindex gnus-treat-display-x-face
+@vindex gnus-treat-display-face
+@vindex gnus-treat-emphasize
+@vindex gnus-treat-fill-article
+@vindex gnus-treat-fill-long-lines
+@vindex gnus-treat-hide-boring-headers
+@vindex gnus-treat-hide-citation
+@vindex gnus-treat-hide-citation-maybe
+@vindex gnus-treat-hide-headers
+@vindex gnus-treat-hide-signature
+@vindex gnus-treat-strip-banner
+@vindex gnus-treat-strip-list-identifiers
+@vindex gnus-treat-highlight-citation
+@vindex gnus-treat-highlight-headers
+@vindex gnus-treat-highlight-signature
+@vindex gnus-treat-play-sounds
+@vindex gnus-treat-x-pgp-sig
+@vindex gnus-treat-unfold-headers
+@vindex gnus-treat-fold-headers
+@vindex gnus-treat-fold-newsgroups
+@vindex gnus-treat-leading-whitespace
+@end ifinfo
+
+The following treatment options are available. The easiest way to
+customize this is to examine the @code{gnus-article-treat} customization
+group. Values in parenthesis are suggested sensible values. Others are
+possible but those listed are probably sufficient for most people.
+
+@table @code
+@item gnus-treat-buttonize (t, integer)
+@item gnus-treat-buttonize-head (head)
+
+@xref{Article Buttons}.
+
+@item gnus-treat-capitalize-sentences (t, integer)
+@item gnus-treat-overstrike (t, integer)
+@item gnus-treat-strip-cr (t, integer)
+@item gnus-treat-strip-headers-in-body (t, integer)
+@item gnus-treat-strip-leading-blank-lines (t, first, integer)
+@item gnus-treat-strip-multiple-blank-lines (t, integer)
+@item gnus-treat-strip-pem (t, last, integer)
+@item gnus-treat-strip-trailing-blank-lines (t, last, integer)
+@item gnus-treat-unsplit-urls (t, integer)
+@item gnus-treat-wash-html (t, integer)
+
+@xref{Article Washing}.
+
+@item gnus-treat-date (head)
+
+This will transform/add date headers according to the
+@code{gnus-article-date-headers} variable. This is a list of Date
+headers to display. The formats available are:
+
+@table @code
+@item ut
+Universal time, aka GMT, aka ZULU.
+
+@item local
+The user's local time zone.
+
+@item english
+A semi-readable English sentence.
+
+@item lapsed
+The time elapsed since the message was posted.
+
+@item combined-lapsed
+Both the original date header and a (shortened) elapsed time.
+
+@item original
+The original date header.
+
+@item iso8601
+ISO8601 format, i.e., ``2010-11-23T22:05:21''.
+
+@item user-defined
+A format done according to the @code{gnus-article-time-format}
+variable.
+
+@end table
+
+@xref{Article Date}.
+
+@item gnus-treat-from-picon (head)
+@item gnus-treat-mail-picon (head)
+@item gnus-treat-newsgroups-picon (head)
+
+@xref{Picons}.
+
+@item gnus-treat-from-gravatar (head)
+@item gnus-treat-mail-gravatar (head)
+
+@xref{Gravatars}.
+
+@item gnus-treat-display-smileys (t, integer)
+
+@item gnus-treat-body-boundary (head)
+
+@vindex gnus-body-boundary-delimiter
+Adds a delimiter between header and body, the string used as delimiter
+is controlled by @code{gnus-body-boundary-delimiter}.
+
+@xref{Smileys}.
+
+@vindex gnus-treat-display-x-face
+@item gnus-treat-display-x-face (head)
+
+@xref{X-Face}.
+
+@vindex gnus-treat-display-face
+@item gnus-treat-display-face (head)
+
+@xref{Face}.
+
+@vindex gnus-treat-emphasize
+@item gnus-treat-emphasize (t, head, integer)
+@vindex gnus-treat-fill-article
+@item gnus-treat-fill-article (t, integer)
+@vindex gnus-treat-fill-long-lines
+@item gnus-treat-fill-long-lines (t, integer)
+@vindex gnus-treat-hide-boring-headers
+@item gnus-treat-hide-boring-headers (head)
+@vindex gnus-treat-hide-citation
+@item gnus-treat-hide-citation (t, integer)
+@vindex gnus-treat-hide-citation-maybe
+@item gnus-treat-hide-citation-maybe (t, integer)
+@vindex gnus-treat-hide-headers
+@item gnus-treat-hide-headers (head)
+@vindex gnus-treat-hide-signature
+@item gnus-treat-hide-signature (t, last)
+@vindex gnus-treat-strip-banner
+@item gnus-treat-strip-banner (t, last)
+@vindex gnus-treat-strip-list-identifiers
+@item gnus-treat-strip-list-identifiers (head)
+
+@xref{Article Hiding}.
+
+@vindex gnus-treat-highlight-citation
+@item gnus-treat-highlight-citation (t, integer)
+@vindex gnus-treat-highlight-headers
+@item gnus-treat-highlight-headers (head)
+@vindex gnus-treat-highlight-signature
+@item gnus-treat-highlight-signature (t, last, integer)
+
+@xref{Article Highlighting}.
+
+@vindex gnus-treat-play-sounds
+@item gnus-treat-play-sounds
+@item gnus-treat-ansi-sequences (t)
+@vindex gnus-treat-x-pgp-sig
+@item gnus-treat-x-pgp-sig (head)
+
+@vindex gnus-treat-unfold-headers
+@item gnus-treat-unfold-headers (head)
+@vindex gnus-treat-fold-headers
+@item gnus-treat-fold-headers (head)
+@vindex gnus-treat-fold-newsgroups
+@item gnus-treat-fold-newsgroups (head)
+@vindex gnus-treat-leading-whitespace
+@item gnus-treat-leading-whitespace (head)
+
+@xref{Article Header}.
+
+
+@end table
+
+@vindex gnus-part-display-hook
+You can, of course, write your own functions to be called from
+@code{gnus-part-display-hook}. The functions are called narrowed to the
+part, and you can do anything you like, pretty much. There is no
+information that you have to keep in the buffer---you can change
+everything.
+
+
+@node Article Keymap
+@section Article Keymap
+
+Most of the keystrokes in the summary buffer can also be used in the
+article buffer. They should behave as if you typed them in the summary
+buffer, which means that you don't actually have to have a summary
+buffer displayed while reading. You can do it all from the article
+buffer.
+
+@kindex v (Article)
+@cindex keys, reserved for users (Article)
+The key @kbd{v} is reserved for users. You can bind it to some
+command or better use it as a prefix key.
+
+A few additional keystrokes are available:
+
+@table @kbd
+
+@item SPACE
+@kindex SPACE (Article)
+@findex gnus-article-next-page
+Scroll forwards one page (@code{gnus-article-next-page}).
+This is exactly the same as @kbd{h SPACE h}.
+
+@item DEL
+@kindex DEL (Article)
+@findex gnus-article-prev-page
+Scroll backwards one page (@code{gnus-article-prev-page}).
+This is exactly the same as @kbd{h DEL h}.
+
+@item C-c ^
+@kindex C-c ^ (Article)
+@findex gnus-article-refer-article
+If point is in the neighborhood of a @code{Message-ID} and you press
+@kbd{C-c ^}, Gnus will try to get that article from the server
+(@code{gnus-article-refer-article}).
+
+@item C-c C-m
+@kindex C-c C-m (Article)
+@findex gnus-article-mail
+Send a reply to the address near point (@code{gnus-article-mail}). If
+given a prefix, include the mail.
+
+@item s
+@kindex s (Article)
+@findex gnus-article-show-summary
+Reconfigure the buffers so that the summary buffer becomes visible
+(@code{gnus-article-show-summary}).
+
+@item ?
+@kindex ? (Article)
+@findex gnus-article-describe-briefly
+Give a very brief description of the available keystrokes
+(@code{gnus-article-describe-briefly}).
+
+@item TAB
+@kindex TAB (Article)
+@findex gnus-article-next-button
+Go to the next button, if any (@code{gnus-article-next-button}). This
+only makes sense if you have buttonizing turned on.
+
+@item M-TAB
+@kindex M-TAB (Article)
+@findex gnus-article-prev-button
+Go to the previous button, if any (@code{gnus-article-prev-button}).
+
+@item R
+@kindex R (Article)
+@findex gnus-article-reply-with-original
+Send a reply to the current article and yank the current article
+(@code{gnus-article-reply-with-original}). If the region is active,
+only yank the text in the region.
+
+@item S W
+@kindex S W (Article)
+@findex gnus-article-wide-reply-with-original
+Send a wide reply to the current article and yank the current article
+(@code{gnus-article-wide-reply-with-original}). If the region is
+active, only yank the text in the region.
+
+@item F
+@kindex F (Article)
+@findex gnus-article-followup-with-original
+Send a followup to the current article and yank the current article
+(@code{gnus-article-followup-with-original}). If the region is active,
+only yank the text in the region.
+
+
+@end table
+
+
+@node Misc Article
+@section Misc Article
+
+@table @code
+
+@item gnus-single-article-buffer
+@vindex gnus-single-article-buffer
+@cindex article buffers, several
+If non-@code{nil}, use the same article buffer for all the groups.
+(This is the default.) If @code{nil}, each group will have its own
+article buffer.
+
+@item gnus-widen-article-window
+@cindex gnus-widen-article-window
+If non-@code{nil}, selecting the article buffer with the @kbd{h}
+command will ``widen'' the article window to take the entire frame.
+
+@vindex gnus-article-decode-hook
+@item gnus-article-decode-hook
+@cindex @acronym{MIME}
+Hook used to decode @acronym{MIME} articles. The default value is
+@code{(article-decode-charset article-decode-encoded-words)}
+
+@vindex gnus-article-prepare-hook
+@item gnus-article-prepare-hook
+This hook is called right after the article has been inserted into the
+article buffer. It is mainly intended for functions that do something
+depending on the contents; it should probably not be used for changing
+the contents of the article buffer.
+
+@item gnus-article-mode-hook
+@vindex gnus-article-mode-hook
+Hook called in article mode buffers.
+
+@item gnus-article-mode-syntax-table
+@vindex gnus-article-mode-syntax-table
+Syntax table used in article buffers. It is initialized from
+@code{text-mode-syntax-table}.
+
+@vindex gnus-article-over-scroll
+@item gnus-article-over-scroll
+If non-@code{nil}, allow scrolling the article buffer even when there
+no more new text to scroll in. The default is @code{nil}.
+
+@vindex gnus-article-mode-line-format
+@item gnus-article-mode-line-format
+This variable is a format string along the same lines as
+@code{gnus-summary-mode-line-format} (@pxref{Summary Buffer Mode
+Line}). It accepts the same format specifications as that variable,
+with two extensions:
+
+@table @samp
+
+@item w
+The @dfn{wash status} of the article. This is a short string with one
+character for each possible article wash operation that may have been
+performed. The characters and their meaning:
+
+@table @samp
+
+@item c
+Displayed when cited text may be hidden in the article buffer.
+
+@item h
+Displayed when headers are hidden in the article buffer.
+
+@item p
+Displayed when article is digitally signed or encrypted, and Gnus has
+hidden the security headers. (N.B. does not tell anything about
+security status, i.e., good or bad signature.)
+
+@item s
+Displayed when the signature has been hidden in the Article buffer.
+
+@item o
+Displayed when Gnus has treated overstrike characters in the article buffer.
+
+@item e
+Displayed when Gnus has treated emphasized strings in the article buffer.
+
+@end table
+
+@item m
+The number of @acronym{MIME} parts in the article.
+
+@end table
+
+@vindex gnus-break-pages
+
+@item gnus-break-pages
+Controls whether @dfn{page breaking} is to take place. If this variable
+is non-@code{nil}, the articles will be divided into pages whenever a
+page delimiter appears in the article. If this variable is @code{nil},
+paging will not be done.
+
+@item gnus-page-delimiter
+@vindex gnus-page-delimiter
+This is the delimiter mentioned above. By default, it is @samp{^L}
+(formfeed).
+
+@cindex IDNA
+@cindex internationalized domain names
+@vindex gnus-use-idna
+@item gnus-use-idna
+This variable controls whether Gnus performs IDNA decoding of
+internationalized domain names inside @samp{From}, @samp{To} and
+@samp{Cc} headers. @xref{IDNA, ,IDNA,message, The Message Manual},
+for how to compose such messages. This requires
+@uref{http://www.gnu.org/software/libidn/, GNU Libidn}, and this
+variable is only enabled if you have installed it.
+
+@vindex gnus-inhibit-images
+@item gnus-inhibit-images
+If this is non-@code{nil}, inhibit displaying of images inline in the
+article body. It is effective to images that are in articles as
+@acronym{MIME} parts, and images in @acronym{HTML} articles rendered
+when @code{mm-text-html-renderer} (@pxref{Display Customization,
+,Display Customization, emacs-mime, The Emacs MIME Manual}) is
+@code{shr} or @code{gnus-w3m}.
+
+@end table
+
+
+@node Composing Messages
+@chapter Composing Messages
+@cindex composing messages
+@cindex messages
+@cindex mail
+@cindex sending mail
+@cindex reply
+@cindex followup
+@cindex post
+@cindex using gpg
+@cindex using s/mime
+@cindex using smime
+
+@kindex C-c C-c (Post)
+All commands for posting and mailing will put you in a message buffer
+where you can edit the article all you like, before you send the
+article by pressing @kbd{C-c C-c}. @xref{Top, , Overview, message,
+Message Manual}. Where the message will be posted/mailed to depends
+on your setup (@pxref{Posting Server}).
+
+@menu
+* Mail:: Mailing and replying.
+* Posting Server:: What server should you post and mail via?
+* POP before SMTP:: You cannot send a mail unless you read a mail.
+* Mail and Post:: Mailing and posting at the same time.
+* Archived Messages:: Where Gnus stores the messages you've sent.
+* Posting Styles:: An easier way to specify who you are.
+* Drafts:: Postponing messages and rejected messages.
+* Rejected Articles:: What happens if the server doesn't like your article?
+* Signing and encrypting:: How to compose secure messages.
+@end menu
+
+Also @pxref{Canceling and Superseding} for information on how to
+remove articles you shouldn't have posted.
+
+
+@node Mail
+@section Mail
+
+Variables for customizing outgoing mail:
+
+@table @code
+@item gnus-uu-digest-headers
+@vindex gnus-uu-digest-headers
+List of regexps to match headers included in digested messages. The
+headers will be included in the sequence they are matched. If
+@code{nil} include all headers.
+
+@item gnus-add-to-list
+@vindex gnus-add-to-list
+If non-@code{nil}, add a @code{to-list} group parameter to mail groups
+that have none when you do a @kbd{a}.
+
+@item gnus-confirm-mail-reply-to-news
+@vindex gnus-confirm-mail-reply-to-news
+If non-@code{nil}, Gnus will ask you for a confirmation when you are
+about to reply to news articles by mail. If it is @code{nil}, nothing
+interferes in what you want to do. This can also be a function
+receiving the group name as the only parameter which should return
+non-@code{nil} if a confirmation is needed, or a regular expression
+matching group names, where confirmation should be asked for.
+
+If you find yourself never wanting to reply to mail, but occasionally
+press @kbd{R} anyway, this variable might be for you.
+
+@item gnus-confirm-treat-mail-like-news
+@vindex gnus-confirm-treat-mail-like-news
+If non-@code{nil}, Gnus also requests confirmation according to
+@code{gnus-confirm-mail-reply-to-news} when replying to mail. This is
+useful for treating mailing lists like newsgroups.
+
+@end table
+
+
+@node Posting Server
+@section Posting Server
+
+When you press those magical @kbd{C-c C-c} keys to ship off your latest
+(extremely intelligent, of course) article, where does it go?
+
+Thank you for asking. I hate you.
+
+It can be quite complicated.
+
+@vindex gnus-post-method
+When posting news, Message usually invokes @code{message-send-news}
+(@pxref{News Variables, , News Variables, message, Message Manual}).
+Normally, Gnus will post using the same select method as you're
+reading from (which might be convenient if you're reading lots of
+groups from different private servers). However. If the server
+you're reading from doesn't allow posting, just reading, you probably
+want to use some other server to post your (extremely intelligent and
+fabulously interesting) articles. You can then set the
+@code{gnus-post-method} to some other method:
+
+@lisp
+(setq gnus-post-method '(nnspool ""))
+@end lisp
+
+Now, if you've done this, and then this server rejects your article, or
+this server is down, what do you do then? To override this variable you
+can use a non-zero prefix to the @kbd{C-c C-c} command to force using
+the ``current'' server, to get back the default behavior, for posting.
+
+If you give a zero prefix (i.e., @kbd{C-u 0 C-c C-c}) to that command,
+Gnus will prompt you for what method to use for posting.
+
+You can also set @code{gnus-post-method} to a list of select methods.
+If that's the case, Gnus will always prompt you for what method to use
+for posting.
+
+Finally, if you want to always post using the native select method,
+you can set this variable to @code{native}.
+
+@vindex message-send-mail-function
+When sending mail, Message invokes the function specified by the
+variable @code{message-send-mail-function}. Gnus tries to set it to a
+value suitable for your system.
+@xref{Mail Variables, ,Mail Variables,message,Message manual}, for more
+information.
+
+
+@node POP before SMTP
+@section POP before SMTP
+@cindex pop before smtp
+@findex mail-source-touch-pop
+
+Does your @acronym{ISP} use @acronym{POP}-before-@acronym{SMTP}
+authentication? This authentication method simply requires you to
+contact the @acronym{POP} server before sending email. To do that,
+put the following lines in your @file{~/.gnus.el} file:
+
+@lisp
+(add-hook 'message-send-mail-hook 'mail-source-touch-pop)
+@end lisp
+
+@noindent
+The @code{mail-source-touch-pop} function does @acronym{POP}
+authentication according to the value of @code{mail-sources} without
+fetching mails, just before sending a mail. @xref{Mail Sources}.
+
+If you have two or more @acronym{POP} mail servers set in
+@code{mail-sources}, you may want to specify one of them to
+@code{mail-source-primary-source} as the @acronym{POP} mail server to be
+used for the @acronym{POP}-before-@acronym{SMTP} authentication. If it
+is your primary @acronym{POP} mail server (i.e., you are fetching mails
+mainly from that server), you can set it permanently as follows:
+
+@lisp
+(setq mail-source-primary-source
+ '(pop :server "pop3.mail.server"
+ :password "secret"))
+@end lisp
+
+@noindent
+Otherwise, bind it dynamically only when performing the
+@acronym{POP}-before-@acronym{SMTP} authentication as follows:
+
+@lisp
+(add-hook 'message-send-mail-hook
+ (lambda ()
+ (let ((mail-source-primary-source
+ '(pop :server "pop3.mail.server"
+ :password "secret")))
+ (mail-source-touch-pop))))
+@end lisp
+
+
+@node Mail and Post
+@section Mail and Post
+
+Here's a list of variables relevant to both mailing and
+posting:
+
+@table @code
+@item gnus-mailing-list-groups
+@findex gnus-mailing-list-groups
+@cindex mailing lists
+
+If your news server offers groups that are really mailing lists
+gatewayed to the @acronym{NNTP} server, you can read those groups without
+problems, but you can't post/followup to them without some difficulty.
+One solution is to add a @code{to-address} to the group parameters
+(@pxref{Group Parameters}). An easier thing to do is set the
+@code{gnus-mailing-list-groups} to a regexp that matches the groups that
+really are mailing lists. Then, at least, followups to the mailing
+lists will work most of the time. Posting to these groups (@kbd{a}) is
+still a pain, though.
+
+@item gnus-user-agent
+@vindex gnus-user-agent
+@cindex User-Agent
+
+This variable controls which information should be exposed in the
+User-Agent header. It can be a list of symbols or a string. Valid
+symbols are @code{gnus} (show Gnus version) and @code{emacs} (show Emacs
+version). In addition to the Emacs version, you can add @code{codename}
+(show (S)XEmacs codename) or either @code{config} (show system
+configuration) or @code{type} (show system type). If you set it to a
+string, be sure to use a valid format, see RFC 2616.
+
+@end table
+
+You may want to do spell-checking on messages that you send out. Or, if
+you don't want to spell-check by hand, you could add automatic
+spell-checking via the @code{ispell} package:
+
+@cindex ispell
+@findex ispell-message
+@lisp
+(add-hook 'message-send-hook 'ispell-message)
+@end lisp
+
+If you want to change the @code{ispell} dictionary based on what group
+you're in, you could say something like the following:
+
+@lisp
+(add-hook 'gnus-select-group-hook
+ (lambda ()
+ (cond
+ ((string-match
+ "^de\\." (gnus-group-real-name gnus-newsgroup-name))
+ (ispell-change-dictionary "deutsch"))
+ (t
+ (ispell-change-dictionary "english")))))
+@end lisp
+
+Modify to suit your needs.
+
+@vindex gnus-message-highlight-citation
+If @code{gnus-message-highlight-citation} is @code{t}, different levels of
+citations are highlighted like in Gnus article buffers also in message
+mode buffers.
+
+@node Archived Messages
+@section Archived Messages
+@cindex archived messages
+@cindex sent messages
+
+Gnus provides a few different methods for storing the mail and news you
+send. The default method is to use the @dfn{archive virtual server} to
+store the messages. If you want to disable this completely, the
+@code{gnus-message-archive-group} variable should be @code{nil}. The
+default is @code{"sent.%Y-%m"}, which gives you one archive group per month.
+
+For archiving interesting messages in a group you read, see the
+@kbd{B c} (@code{gnus-summary-copy-article}) command (@pxref{Mail
+Group Commands}).
+
+@vindex gnus-message-archive-method
+@code{gnus-message-archive-method} says what virtual server Gnus is to
+use to store sent messages. The default is @code{"archive"}, and when
+actually being used it is expanded into:
+
+@lisp
+(nnfolder "archive"
+ (nnfolder-directory "~/Mail/archive")
+ (nnfolder-active-file "~/Mail/archive/active")
+ (nnfolder-get-new-mail nil)
+ (nnfolder-inhibit-expiry t))
+@end lisp
+
+@quotation
+@vindex gnus-update-message-archive-method
+Note: a server like this is saved in the @file{~/.newsrc.eld} file first
+so that it may be used as a real method of the server which is named
+@code{"archive"} (that is, for the case where
+@code{gnus-message-archive-method} is set to @code{"archive"}) ever
+since. If it once has been saved, it will never be updated by default
+even if you change the value of @code{gnus-message-archive-method}
+afterward. Therefore, the server @code{"archive"} doesn't necessarily
+mean the @code{nnfolder} server like this at all times. If you want the
+saved method to reflect always the value of
+@code{gnus-message-archive-method}, set the
+@code{gnus-update-message-archive-method} variable to a non-@code{nil}
+value. The default value of this variable is @code{nil}.
+@end quotation
+
+You can, however, use any mail select method (@code{nnml},
+@code{nnmbox}, etc.). @code{nnfolder} is a quite likable select method
+for doing this sort of thing, though. If you don't like the default
+directory chosen, you could say something like:
+
+@lisp
+(setq gnus-message-archive-method
+ '(nnfolder "archive"
+ (nnfolder-inhibit-expiry t)
+ (nnfolder-active-file "~/News/sent-mail/active")
+ (nnfolder-directory "~/News/sent-mail/")))
+@end lisp
+
+@vindex gnus-message-archive-group
+@cindex Gcc
+Gnus will insert @code{Gcc} headers in all outgoing messages that point
+to one or more group(s) on that server. Which group to use is
+determined by the @code{gnus-message-archive-group} variable.
+
+This variable can be used to do the following:
+
+@table @asis
+@item a string
+Messages will be saved in that group.
+
+Note that you can include a select method in the group name, then the
+message will not be stored in the select method given by
+@code{gnus-message-archive-method}, but in the select method specified
+by the group name, instead. Suppose @code{gnus-message-archive-method}
+has the default value shown above. Then setting
+@code{gnus-message-archive-group} to @code{"foo"} means that outgoing
+messages are stored in @samp{nnfolder+archive:foo}, but if you use the
+value @code{"nnml:foo"}, then outgoing messages will be stored in
+@samp{nnml:foo}.
+
+@item a list of strings
+Messages will be saved in all those groups.
+
+@item an alist of regexps, functions and forms
+When a key ``matches'', the result is used.
+
+@item @code{nil}
+No message archiving will take place.
+@end table
+
+Let's illustrate:
+
+Just saving to a single group called @samp{MisK}:
+@lisp
+(setq gnus-message-archive-group "MisK")
+@end lisp
+
+Saving to two groups, @samp{MisK} and @samp{safe}:
+@lisp
+(setq gnus-message-archive-group '("MisK" "safe"))
+@end lisp
+
+Save to different groups based on what group you are in:
+@lisp
+(setq gnus-message-archive-group
+ '(("^alt" "sent-to-alt")
+ ("mail" "sent-to-mail")
+ (".*" "sent-to-misc")))
+@end lisp
+
+More complex stuff:
+@lisp
+(setq gnus-message-archive-group
+ '((if (message-news-p)
+ "misc-news"
+ "misc-mail")))
+@end lisp
+
+How about storing all news messages in one file, but storing all mail
+messages in one file per month:
+
+@lisp
+(setq gnus-message-archive-group
+ '((if (message-news-p)
+ "misc-news"
+ (concat "mail." (format-time-string "%Y-%m")))))
+@end lisp
+
+Now, when you send a message off, it will be stored in the appropriate
+group. (If you want to disable storing for just one particular message,
+you can just remove the @code{Gcc} header that has been inserted.) The
+archive group will appear in the group buffer the next time you start
+Gnus, or the next time you press @kbd{F} in the group buffer. You can
+enter it and read the articles in it just like you'd read any other
+group. If the group gets really big and annoying, you can simply rename
+if (using @kbd{G r} in the group buffer) to something
+nice---@samp{misc-mail-september-1995}, or whatever. New messages will
+continue to be stored in the old (now empty) group.
+
+@table @code
+@item gnus-gcc-mark-as-read
+@vindex gnus-gcc-mark-as-read
+If non-@code{nil}, automatically mark @code{Gcc} articles as read.
+
+@item gnus-gcc-externalize-attachments
+@vindex gnus-gcc-externalize-attachments
+If @code{nil}, attach files as normal parts in Gcc copies; if a regexp
+and matches the Gcc group name, attach files as external parts; if it is
+@code{all}, attach local files as external parts; if it is other
+non-@code{nil}, the behavior is the same as @code{all}, but it may be
+changed in the future.
+
+@item gnus-gcc-self-resent-messages
+@vindex gnus-gcc-self-resent-messages
+Like the @code{gcc-self} group parameter, applied only for unmodified
+messages that @code{gnus-summary-resend-message} (@pxref{Summary Mail
+Commands}) resends. Non-@code{nil} value of this variable takes
+precedence over any existing @code{Gcc} header.
+
+If this is @code{none}, no @code{Gcc} copy will be made. If this is
+@code{t}, messages resent will be @code{Gcc} copied to the current
+group. If this is a string, it specifies a group to which resent
+messages will be @code{Gcc} copied. If this is @code{nil}, @code{Gcc}
+will be done according to existing @code{Gcc} header(s), if any. If
+this is @code{no-gcc-self}, that is the default, resent messages will be
+@code{Gcc} copied to groups that existing @code{Gcc} header specifies,
+except for the current group.
+
+@item gnus-gcc-pre-body-encode-hook
+@vindex gnus-gcc-pre-body-encode-hook
+@itemx gnus-gcc-post-body-encode-hook
+@vindex gnus-gcc-post-body-encode-hook
+
+These hooks are run before/after encoding the message body of the Gcc
+copy of a sent message. The current buffer (when the hook is run)
+contains the message including the message header. Changes made to
+the message will only affect the Gcc copy, but not the original
+message. You can use these hooks to edit the copy (and influence
+subsequent transformations), e.g., remove MML secure tags
+(@pxref{Signing and encrypting}).
+
+@end table
+
+
+@node Posting Styles
+@section Posting Styles
+@cindex posting styles
+@cindex styles
+
+All them variables, they make my head swim.
+
+So what if you want a different @code{Organization} and signature based
+on what groups you post to? And you post both from your home machine
+and your work machine, and you want different @code{From} lines, and so
+on?
+
+@vindex gnus-posting-styles
+One way to do stuff like that is to write clever hooks that change the
+variables you need to have changed. That's a bit boring, so somebody
+came up with the bright idea of letting the user specify these things in
+a handy alist. Here's an example of a @code{gnus-posting-styles}
+variable:
+
+@lisp
+((".*"
+ (signature "Peace and happiness")
+ (organization "What me?"))
+ ("^comp"
+ (signature "Death to everybody"))
+ ("comp.emacs.i-love-it"
+ (organization "Emacs is it")))
+@end lisp
+
+As you might surmise from this example, this alist consists of several
+@dfn{styles}. Each style will be applicable if the first element
+``matches'', in some form or other. The entire alist will be iterated
+over, from the beginning towards the end, and each match will be
+applied, which means that attributes in later styles that match override
+the same attributes in earlier matching styles. So
+@samp{comp.programming.literate} will have the @samp{Death to everybody}
+signature and the @samp{What me?} @code{Organization} header.
+
+The first element in each style is called the @code{match}. If it's a
+string, then Gnus will try to regexp match it against the group name.
+If it is the form @code{(header @var{match} @var{regexp})}, then Gnus
+will look in the original article for a header whose name is
+@var{match} and compare that @var{regexp}. @var{match} and
+@var{regexp} are strings. (The original article is the one you are
+replying or following up to. If you are not composing a reply or a
+followup, then there is nothing to match against.) If the
+@code{match} is a function symbol, that function will be called with
+no arguments. If it's a variable symbol, then the variable will be
+referenced. If it's a list, then that list will be @code{eval}ed. In
+any case, if this returns a non-@code{nil} value, then the style is
+said to @dfn{match}.
+
+Each style may contain an arbitrary amount of @dfn{attributes}. Each
+attribute consists of a @code{(@var{name} @var{value})} pair. In
+addition, you can also use the @code{(@var{name} :file @var{value})}
+form or the @code{(@var{name} :value @var{value})} form. Where
+@code{:file} signifies @var{value} represents a file name and its
+contents should be used as the attribute value, @code{:value} signifies
+@var{value} does not represent a file name explicitly. The attribute
+name can be one of:
+
+@itemize @bullet
+@item @code{signature}
+@item @code{signature-file}
+@item @code{x-face-file}
+@item @code{address}, overriding @code{user-mail-address}
+@item @code{name}, overriding @code{(user-full-name)}
+@item @code{body}
+@end itemize
+
+Note that the @code{signature-file} attribute honors the variable
+@code{message-signature-directory}.
+
+The attribute name can also be a string or a symbol. In that case,
+this will be used as a header name, and the value will be inserted in
+the headers of the article; if the value is @code{nil}, the header
+name will be removed. If the attribute name is @code{eval}, the form
+is evaluated, and the result is thrown away.
+
+The attribute value can be a string, a function with zero arguments
+(the return value will be used), a variable (its value will be used)
+or a list (it will be @code{eval}ed and the return value will be
+used). The functions and sexps are called/@code{eval}ed in the
+message buffer that is being set up. The headers of the current
+article are available through the @code{message-reply-headers}
+variable, which is a vector of the following headers: number subject
+from date id references chars lines xref extra.
+
+In the case of a string value, if the @code{match} is a regular
+expression, or if it takes the form @code{(header @var{match}
+@var{regexp})}, a @samp{gnus-match-substitute-replacement} is proceed
+on the value to replace the positional parameters @samp{\@var{n}} by
+the corresponding parenthetical matches (see @xref{Replacing Match,,
+Replacing the Text that Matched, elisp, The Emacs Lisp Reference
+Manual}.)
+
+@vindex message-reply-headers
+
+If you wish to check whether the message you are about to compose is
+meant to be a news article or a mail message, you can check the values
+of the @code{message-news-p} and @code{message-mail-p} functions.
+
+@findex message-mail-p
+@findex message-news-p
+
+So here's a new example:
+
+@lisp
+(setq gnus-posting-styles
+ '((".*"
+ (signature-file "~/.signature")
+ (name "User Name")
+ (x-face-file "~/.xface")
+ (x-url (getenv "WWW_HOME"))
+ (organization "People's Front Against MWM"))
+ ("^rec.humor"
+ (signature my-funny-signature-randomizer))
+ ((equal (system-name) "gnarly") ;; @r{A form}
+ (signature my-quote-randomizer))
+ (message-news-p ;; @r{A function symbol}
+ (signature my-news-signature))
+ (window-system ;; @r{A value symbol}
+ ("X-Window-System" (format "%s" window-system)))
+ ;; @r{If I'm replying to Larsi, set the Organization header.}
+ ((header "from" "larsi.*org")
+ (Organization "Somewhere, Inc."))
+ ;; @r{Reply to a message from the same subaddress the message}
+ ;; @r{was sent to.}
+ ((header "x-original-to" "me\\(\\+.+\\)@@example.org")
+ (address "me\\1@@example.org"))
+ ((posting-from-work-p) ;; @r{A user defined function}
+ (signature-file "~/.work-signature")
+ (address "user@@bar.foo")
+ (body "You are fired.\n\nSincerely, your boss.")
+ ("X-Message-SMTP-Method" "smtp smtp.example.org 587")
+ (organization "Important Work, Inc"))
+ ("nnml:.*"
+ (From (with-current-buffer gnus-article-buffer
+ (message-fetch-field "to"))))
+ ("^nn.+:"
+ (signature-file "~/.mail-signature"))))
+@end lisp
+
+The @samp{nnml:.*} rule means that you use the @code{To} address as the
+@code{From} address in all your outgoing replies, which might be handy
+if you fill many roles.
+You may also use @code{message-alternative-emails} instead.
+@xref{Message Headers, ,Message Headers, message, Message Manual}.
+
+Of particular interest in the ``work-mail'' style is the
+@samp{X-Message-SMTP-Method} header. It specifies how to send the
+outgoing email. You may want to sent certain emails through certain
+@acronym{SMTP} servers due to company policies, for instance.
+@xref{Mail Variables, ,Message Variables, message, Message Manual}.
+
+
+@node Drafts
+@section Drafts
+@cindex drafts
+
+If you are writing a message (mail or news) and suddenly remember that
+you have a steak in the oven (or some pesto in the food processor, you
+craaazy vegetarians), you'll probably wish there was a method to save
+the message you are writing so that you can continue editing it some
+other day, and send it when you feel its finished.
+
+Well, don't worry about it. Whenever you start composing a message of
+some sort using the Gnus mail and post commands, the buffer you get will
+automatically associate to an article in a special @dfn{draft} group.
+If you save the buffer the normal way (@kbd{C-x C-s}, for instance), the
+article will be saved there. (Auto-save files also go to the draft
+group.)
+
+@cindex nndraft
+@vindex nndraft-directory
+The draft group is a special group (which is implemented as an
+@code{nndraft} group, if you absolutely have to know) called
+@samp{nndraft:drafts}. The variable @code{nndraft-directory} says where
+@code{nndraft} is to store its files. What makes this group special is
+that you can't tick any articles in it or mark any articles as
+read---all articles in the group are permanently unread.
+
+If the group doesn't exist, it will be created and you'll be subscribed
+to it. The only way to make it disappear from the Group buffer is to
+unsubscribe it. The special properties of the draft group comes from
+a group property (@pxref{Group Parameters}), and if lost the group
+behaves like any other group. This means the commands below will not
+be available. To restore the special properties of the group, the
+simplest way is to kill the group, using @kbd{C-k}, and restart
+Gnus. The group is automatically created again with the
+correct parameters. The content of the group is not lost.
+
+@c @findex gnus-dissociate-buffer-from-draft
+@c @kindex C-c M-d (Mail)
+@c @kindex C-c M-d (Post)
+@c @findex gnus-associate-buffer-with-draft
+@c @kindex C-c C-d (Mail)
+@c @kindex C-c C-d (Post)
+@c If you're writing some super-secret message that you later want to
+@c encode with PGP before sending, you may wish to turn the auto-saving
+@c (and association with the draft group) off. You never know who might be
+@c interested in reading all your extremely valuable and terribly horrible
+@c and interesting secrets. The @kbd{C-c M-d}
+@c (@code{gnus-dissociate-buffer-from-draft}) command does that for you.
+@c If you change your mind and want to turn the auto-saving back on again,
+@c @kbd{C-c C-d} (@code{gnus-associate-buffer-with-draft} does that.
+@c
+@c @vindex gnus-use-draft
+@c To leave association with the draft group off by default, set
+@c @code{gnus-use-draft} to @code{nil}. It is @code{t} by default.
+
+@findex gnus-draft-edit-message
+@kindex D e (Draft)
+When you want to continue editing the article, you simply enter the
+draft group and push @kbd{D e} (@code{gnus-draft-edit-message}) to do
+that. You will be placed in a buffer where you left off.
+
+Rejected articles will also be put in this draft group (@pxref{Rejected
+Articles}).
+
+@findex gnus-draft-send-all-messages
+@kindex D s (Draft)
+@findex gnus-draft-send-message
+@kindex D S (Draft)
+If you have lots of rejected messages you want to post (or mail) without
+doing further editing, you can use the @kbd{D s} command
+(@code{gnus-draft-send-message}). This command understands the
+process/prefix convention (@pxref{Process/Prefix}). The @kbd{D S}
+command (@code{gnus-draft-send-all-messages}) will ship off all messages
+in the buffer.
+
+@findex gnus-draft-toggle-sending
+@kindex D t (Draft)
+If you have some messages that you wish not to send, you can use the
+@kbd{D t} (@code{gnus-draft-toggle-sending}) command to mark the message
+as unsendable. This is a toggling command.
+
+Finally, if you want to delete a draft, use the normal @kbd{B DEL}
+command (@pxref{Mail Group Commands}).
+
+
+@node Rejected Articles
+@section Rejected Articles
+@cindex rejected articles
+
+Sometimes a news server will reject an article. Perhaps the server
+doesn't like your face. Perhaps it just feels miserable. Perhaps
+@emph{there be demons}. Perhaps you have included too much cited text.
+Perhaps the disk is full. Perhaps the server is down.
+
+These situations are, of course, totally beyond the control of Gnus.
+(Gnus, of course, loves the way you look, always feels great, has angels
+fluttering around inside of it, doesn't care about how much cited text
+you include, never runs full and never goes down.) So Gnus saves these
+articles until some later time when the server feels better.
+
+The rejected articles will automatically be put in a special draft group
+(@pxref{Drafts}). When the server comes back up again, you'd then
+typically enter that group and send all the articles off.
+
+@node Signing and encrypting
+@section Signing and encrypting
+@cindex using gpg
+@cindex using s/mime
+@cindex using smime
+
+Gnus can digitally sign and encrypt your messages, using vanilla
+@acronym{PGP} format or @acronym{PGP/MIME} or @acronym{S/MIME}. For
+decoding such messages, see the @code{mm-verify-option} and
+@code{mm-decrypt-option} options (@pxref{Security}).
+
+@vindex gnus-message-replysign
+@vindex gnus-message-replyencrypt
+@vindex gnus-message-replysignencrypted
+Often, you would like to sign replies to people who send you signed
+messages. Even more often, you might want to encrypt messages which
+are in reply to encrypted messages. Gnus offers
+@code{gnus-message-replysign} to enable the former, and
+@code{gnus-message-replyencrypt} for the latter. In addition, setting
+@code{gnus-message-replysignencrypted} (on by default) will sign
+automatically encrypted messages.
+
+Instructing @acronym{MML} to perform security operations on a
+@acronym{MIME} part is done using the @kbd{C-c C-m s} key map for
+signing and the @kbd{C-c C-m c} key map for encryption, as follows.
+
+@table @kbd
+
+@item C-c C-m s s
+@kindex C-c C-m s s (Message)
+@findex mml-secure-message-sign-smime
+
+Digitally sign current message using @acronym{S/MIME}.
+
+@item C-c C-m s o
+@kindex C-c C-m s o (Message)
+@findex mml-secure-message-sign-pgp
+
+Digitally sign current message using @acronym{PGP}.
+
+@item C-c C-m s p
+@kindex C-c C-m s p (Message)
+@findex mml-secure-message-sign-pgp
+
+Digitally sign current message using @acronym{PGP/MIME}.
+
+@item C-c C-m c s
+@kindex C-c C-m c s (Message)
+@findex mml-secure-message-encrypt-smime
+
+Digitally encrypt current message using @acronym{S/MIME}.
+
+@item C-c C-m c o
+@kindex C-c C-m c o (Message)
+@findex mml-secure-message-encrypt-pgp
+
+Digitally encrypt current message using @acronym{PGP}.
+
+@item C-c C-m c p
+@kindex C-c C-m c p (Message)
+@findex mml-secure-message-encrypt-pgpmime
+
+Digitally encrypt current message using @acronym{PGP/MIME}.
+
+@item C-c C-m C-n
+@kindex C-c C-m C-n (Message)
+@findex mml-unsecure-message
+Remove security related @acronym{MML} tags from message.
+
+@end table
+
+@xref{Security, ,Security, message, Message Manual}, for more information.
+
+@node Select Methods
+@chapter Select Methods
+@cindex foreign groups
+@cindex select methods
+
+A @dfn{foreign group} is a group not read by the usual (or
+default) means. It could be, for instance, a group from a different
+@acronym{NNTP} server, it could be a virtual group, or it could be your own
+personal mail group.
+
+A foreign group (or any group, really) is specified by a @dfn{name} and
+a @dfn{select method}. To take the latter first, a select method is a
+list where the first element says what back end to use (e.g., @code{nntp},
+@code{nnspool}, @code{nnml}) and the second element is the @dfn{server
+name}. There may be additional elements in the select method, where the
+value may have special meaning for the back end in question.
+
+One could say that a select method defines a @dfn{virtual server}---so
+we do just that (@pxref{Server Buffer}).
+
+The @dfn{name} of the group is the name the back end will recognize the
+group as.
+
+For instance, the group @samp{soc.motss} on the @acronym{NNTP} server
+@samp{some.where.edu} will have the name @samp{soc.motss} and select
+method @code{(nntp "some.where.edu")}. Gnus will call this group
+@samp{nntp+some.where.edu:soc.motss}, even though the @code{nntp}
+back end just knows this group as @samp{soc.motss}.
+
+The different methods all have their peculiarities, of course.
+
+@menu
+* Server Buffer:: Making and editing virtual servers.
+* Getting News:: Reading USENET news with Gnus.
+* Using IMAP:: Reading mail from @acronym{IMAP}.
+* Getting Mail:: Reading your personal mail with Gnus.
+* Browsing the Web:: Getting messages from a plethora of Web sources.
+* Other Sources:: Reading directories, files.
+* Combined Groups:: Combining groups into one group.
+* Email Based Diary:: Using mails to manage diary events in Gnus.
+* Gnus Unplugged:: Reading news and mail offline.
+@end menu
+
+
+@node Server Buffer
+@section Server Buffer
+
+Traditionally, a @dfn{server} is a machine or a piece of software that
+one connects to, and then requests information from. Gnus does not
+connect directly to any real servers, but does all transactions through
+one back end or other. But that's just putting one layer more between
+the actual media and Gnus, so we might just as well say that each
+back end represents a virtual server.
+
+For instance, the @code{nntp} back end may be used to connect to several
+different actual @acronym{NNTP} servers, or, perhaps, to many different ports
+on the same actual @acronym{NNTP} server. You tell Gnus which back end to
+use, and what parameters to set by specifying a @dfn{select method}.
+
+These select method specifications can sometimes become quite
+complicated---say, for instance, that you want to read from the
+@acronym{NNTP} server @samp{news.funet.fi} on port number 13, which
+hangs if queried for @acronym{NOV} headers and has a buggy select. Ahem.
+Anyway, if you had to specify that for each group that used this
+server, that would be too much work, so Gnus offers a way of naming
+select methods, which is what you do in the server buffer.
+
+To enter the server buffer, use the @kbd{^}
+(@code{gnus-group-enter-server-mode}) command in the group buffer.
+
+@menu
+* Server Buffer Format:: You can customize the look of this buffer.
+* Server Commands:: Commands to manipulate servers.
+* Example Methods:: Examples server specifications.
+* Creating a Virtual Server:: An example session.
+* Server Variables:: Which variables to set.
+* Servers and Methods:: You can use server names as select methods.
+* Unavailable Servers:: Some servers you try to contact may be down.
+@end menu
+
+@vindex gnus-server-mode-hook
+@code{gnus-server-mode-hook} is run when creating the server buffer.
+
+
+@node Server Buffer Format
+@subsection Server Buffer Format
+@cindex server buffer format
+
+@vindex gnus-server-line-format
+You can change the look of the server buffer lines by changing the
+@code{gnus-server-line-format} variable. This is a @code{format}-like
+variable, with some simple extensions:
+
+@table @samp
+
+@item h
+How the news is fetched---the back end name.
+
+@item n
+The name of this server.
+
+@item w
+Where the news is to be fetched from---the address.
+
+@item s
+The opened/closed/denied status of the server.
+
+@item a
+Whether this server is agentized.
+@end table
+
+@vindex gnus-server-mode-line-format
+The mode line can also be customized by using the
+@code{gnus-server-mode-line-format} variable (@pxref{Mode Line
+Formatting}). The following specs are understood:
+
+@table @samp
+@item S
+Server name.
+
+@item M
+Server method.
+@end table
+
+Also @pxref{Formatting Variables}.
+
+
+@node Server Commands
+@subsection Server Commands
+@cindex server commands
+
+@table @kbd
+
+@item v
+@kindex v (Server)
+@cindex keys, reserved for users (Server)
+The key @kbd{v} is reserved for users. You can bind it to some
+command or better use it as a prefix key.
+
+@item a
+@kindex a (Server)
+@findex gnus-server-add-server
+Add a new server (@code{gnus-server-add-server}).
+
+@item e
+@kindex e (Server)
+@findex gnus-server-edit-server
+Edit a server (@code{gnus-server-edit-server}).
+
+@item S
+@kindex S (Server)
+@findex gnus-server-show-server
+Show the definition of a server (@code{gnus-server-show-server}).
+
+@item SPACE
+@kindex SPACE (Server)
+@findex gnus-server-read-server
+Browse the current server (@code{gnus-server-read-server}).
+
+@item q
+@kindex q (Server)
+@findex gnus-server-exit
+Return to the group buffer (@code{gnus-server-exit}).
+
+@item k
+@kindex k (Server)
+@findex gnus-server-kill-server
+Kill the current server (@code{gnus-server-kill-server}).
+
+@item y
+@kindex y (Server)
+@findex gnus-server-yank-server
+Yank the previously killed server (@code{gnus-server-yank-server}).
+
+@item c
+@kindex c (Server)
+@findex gnus-server-copy-server
+Copy the current server (@code{gnus-server-copy-server}).
+
+@item l
+@kindex l (Server)
+@findex gnus-server-list-servers
+List all servers (@code{gnus-server-list-servers}).
+
+@item s
+@kindex s (Server)
+@findex gnus-server-scan-server
+Request that the server scan its sources for new articles
+(@code{gnus-server-scan-server}). This is mainly sensible with mail
+servers.
+
+@item g
+@kindex g (Server)
+@findex gnus-server-regenerate-server
+Request that the server regenerate all its data structures
+(@code{gnus-server-regenerate-server}). This can be useful if you have
+a mail back end that has gotten out of sync.
+
+@item z
+@kindex z (Server)
+@findex gnus-server-compact-server
+
+Compact all groups in the server under point
+(@code{gnus-server-compact-server}). Currently implemented only in
+nnml (@pxref{Mail Spool}). This removes gaps between article numbers,
+hence getting a correct total article count.
+
+@end table
+
+Some more commands for closing, disabling, and re-opening servers are
+listed in @ref{Unavailable Servers}.
+
+
+@node Example Methods
+@subsection Example Methods
+
+Most select methods are pretty simple and self-explanatory:
+
+@lisp
+(nntp "news.funet.fi")
+@end lisp
+
+Reading directly from the spool is even simpler:
+
+@lisp
+(nnspool "")
+@end lisp
+
+As you can see, the first element in a select method is the name of the
+back end, and the second is the @dfn{address}, or @dfn{name}, if you
+will.
+
+After these two elements, there may be an arbitrary number of
+@code{(@var{variable} @var{form})} pairs.
+
+To go back to the first example---imagine that you want to read from
+port 15 on that machine. This is what the select method should
+look like then:
+
+@lisp
+(nntp "news.funet.fi" (nntp-port-number 15))
+@end lisp
+
+You should read the documentation to each back end to find out what
+variables are relevant, but here's an @code{nnmh} example:
+
+@code{nnmh} is a mail back end that reads a spool-like structure. Say
+you have two structures that you wish to access: One is your private
+mail spool, and the other is a public one. Here's the possible spec for
+your private mail:
+
+@lisp
+(nnmh "private" (nnmh-directory "~/private/mail/"))
+@end lisp
+
+(This server is then called @samp{private}, but you may have guessed
+that.)
+
+Here's the method for a public spool:
+
+@lisp
+(nnmh "public"
+ (nnmh-directory "/usr/information/spool/")
+ (nnmh-get-new-mail nil))
+@end lisp
+
+@cindex proxy
+@cindex firewall
+
+If you are behind a firewall and only have access to the @acronym{NNTP}
+server from the firewall machine, you can instruct Gnus to @code{rlogin}
+on the firewall machine and connect with
+@uref{http://netcat.sourceforge.net/, netcat} from there to the
+@acronym{NNTP} server.
+Doing this can be rather fiddly, but your virtual server definition
+should probably look something like this:
+
+@lisp
+(nntp "firewall"
+ (nntp-open-connection-function nntp-open-via-rlogin-and-netcat)
+ (nntp-via-address "the.firewall.machine")
+ (nntp-address "the.real.nntp.host"))
+@end lisp
+
+If you want to use the wonderful @code{ssh} program to provide a
+compressed connection over the modem line, you could add the following
+configuration to the example above:
+
+@lisp
+ (nntp-via-rlogin-command "ssh")
+@end lisp
+
+See also @code{nntp-via-rlogin-command-switches}. Here's an example for
+an indirect connection:
+
+@lisp
+(setq gnus-select-method
+ '(nntp "indirect"
+ (nntp-address "news.server.example")
+ (nntp-via-user-name "intermediate_user_name")
+ (nntp-via-address "intermediate.host.example")
+ (nntp-via-rlogin-command "ssh")
+ (nntp-via-rlogin-command-switches ("-C"))
+ (nntp-open-connection-function nntp-open-via-rlogin-and-netcat)))
+@end lisp
+
+This means that you have to have set up @code{ssh-agent} correctly to
+provide automatic authorization, of course.
+
+If you're behind a firewall, but have direct access to the outside world
+through a wrapper command like "runsocks", you could open a socksified
+netcat connection to the news server as follows:
+
+@lisp
+(nntp "outside"
+ (nntp-pre-command "runsocks")
+ (nntp-open-connection-function nntp-open-netcat-stream)
+ (nntp-address "the.news.server"))
+@end lisp
+
+
+@node Creating a Virtual Server
+@subsection Creating a Virtual Server
+
+If you're saving lots of articles in the cache by using persistent
+articles, you may want to create a virtual server to read the cache.
+
+First you need to add a new server. The @kbd{a} command does that. It
+would probably be best to use @code{nnml} to read the cache. You
+could also use @code{nnspool} or @code{nnmh}, though.
+
+Type @kbd{a nnml RET cache RET}.
+
+You should now have a brand new @code{nnml} virtual server called
+@samp{cache}. You now need to edit it to have the right definitions.
+Type @kbd{e} to edit the server. You'll be entered into a buffer that
+will contain the following:
+
+@lisp
+(nnml "cache")
+@end lisp
+
+Change that to:
+
+@lisp
+(nnml "cache"
+ (nnml-directory "~/News/cache/")
+ (nnml-active-file "~/News/cache/active"))
+@end lisp
+
+Type @kbd{C-c C-c} to return to the server buffer. If you now press
+@kbd{RET} over this virtual server, you should be entered into a browse
+buffer, and you should be able to enter any of the groups displayed.
+
+
+@node Server Variables
+@subsection Server Variables
+@cindex server variables
+@cindex server parameters
+
+One sticky point when defining variables (both on back ends and in Emacs
+in general) is that some variables are typically initialized from other
+variables when the definition of the variables is being loaded. If you
+change the ``base'' variable after the variables have been loaded, you
+won't change the ``derived'' variables.
+
+This typically affects directory and file variables. For instance,
+@code{nnml-directory} is @file{~/Mail/} by default, and all @code{nnml}
+directory variables are initialized from that variable, so
+@code{nnml-active-file} will be @file{~/Mail/active}. If you define a
+new virtual @code{nnml} server, it will @emph{not} suffice to set just
+@code{nnml-directory}---you have to explicitly set all the file
+variables to be what you want them to be. For a complete list of
+variables for each back end, see each back end's section later in this
+manual, but here's an example @code{nnml} definition:
+
+@lisp
+(nnml "public"
+ (nnml-directory "~/my-mail/")
+ (nnml-active-file "~/my-mail/active")
+ (nnml-newsgroups-file "~/my-mail/newsgroups"))
+@end lisp
+
+Server variables are often called @dfn{server parameters}.
+
+@node Servers and Methods
+@subsection Servers and Methods
+
+Wherever you would normally use a select method
+(e.g., @code{gnus-secondary-select-method}, in the group select method,
+when browsing a foreign server) you can use a virtual server name
+instead. This could potentially save lots of typing. And it's nice all
+over.
+
+
+@node Unavailable Servers
+@subsection Unavailable Servers
+
+If a server seems to be unreachable, Gnus will mark that server as
+@code{denied}. That means that any subsequent attempt to make contact
+with that server will just be ignored. ``It can't be opened,'' Gnus
+will tell you, without making the least effort to see whether that is
+actually the case or not.
+
+That might seem quite naughty, but it does make sense most of the time.
+Let's say you have 10 groups subscribed to on server
+@samp{nephelococcygia.com}. This server is located somewhere quite far
+away from you and the machine is quite slow, so it takes 1 minute just
+to find out that it refuses connection to you today. If Gnus were to
+attempt to do that 10 times, you'd be quite annoyed, so Gnus won't
+attempt to do that. Once it has gotten a single ``connection refused'',
+it will regard that server as ``down''.
+
+So, what happens if the machine was only feeling unwell temporarily?
+How do you test to see whether the machine has come up again?
+
+You jump to the server buffer (@pxref{Server Buffer}) and poke it
+with the following commands:
+
+@table @kbd
+
+@item O
+@kindex O (Server)
+@findex gnus-server-open-server
+Try to establish connection to the server on the current line
+(@code{gnus-server-open-server}).
+
+@item C
+@kindex C (Server)
+@findex gnus-server-close-server
+Close the connection (if any) to the server
+(@code{gnus-server-close-server}).
+
+@item D
+@kindex D (Server)
+@findex gnus-server-deny-server
+Mark the current server as unreachable
+(@code{gnus-server-deny-server}).
+
+@item M-o
+@kindex M-o (Server)
+@findex gnus-server-open-all-servers
+Open the connections to all servers in the buffer
+(@code{gnus-server-open-all-servers}).
+
+@item M-c
+@kindex M-c (Server)
+@findex gnus-server-close-all-servers
+Close the connections to all servers in the buffer
+(@code{gnus-server-close-all-servers}).
+
+@item R
+@kindex R (Server)
+@findex gnus-server-remove-denials
+Remove all marks to whether Gnus was denied connection from any servers
+(@code{gnus-server-remove-denials}).
+
+@item c
+@kindex c (Server)
+@findex gnus-server-copy-server
+Copy a server and give it a new name
+(@code{gnus-server-copy-server}). This can be useful if you have a
+complex method definition, and want to use the same definition towards
+a different (physical) server.
+
+@item L
+@kindex L (Server)
+@findex gnus-server-offline-server
+Set server status to offline (@code{gnus-server-offline-server}).
+
+@end table
+
+
+@node Getting News
+@section Getting News
+@cindex reading news
+@cindex news back ends
+
+A newsreader is normally used for reading news. Gnus currently provides
+only two methods of getting news---it can read from an @acronym{NNTP} server,
+or it can read from a local spool.
+
+@menu
+* NNTP:: Reading news from an @acronym{NNTP} server.
+* News Spool:: Reading news from the local spool.
+@end menu
+
+
+@node NNTP
+@subsection NNTP
+@cindex nntp
+
+Subscribing to a foreign group from an @acronym{NNTP} server is rather easy.
+You just specify @code{nntp} as method and the address of the @acronym{NNTP}
+server as the, uhm, address.
+
+If the @acronym{NNTP} server is located at a non-standard port, setting the
+third element of the select method to this port number should allow you
+to connect to the right port. You'll have to edit the group info for
+that (@pxref{Foreign Groups}).
+
+The name of the foreign group can be the same as a native group. In
+fact, you can subscribe to the same group from as many different servers
+you feel like. There will be no name collisions.
+
+The following variables can be used to create a virtual @code{nntp}
+server:
+
+@table @code
+
+@item nntp-server-opened-hook
+@vindex nntp-server-opened-hook
+@cindex @sc{mode reader}
+@cindex authinfo
+@cindex authentication
+@cindex nntp authentication
+@findex nntp-send-authinfo
+@findex nntp-send-mode-reader
+is run after a connection has been made. It can be used to send
+commands to the @acronym{NNTP} server after it has been contacted. By
+default it sends the command @code{MODE READER} to the server with the
+@code{nntp-send-mode-reader} function. This function should always be
+present in this hook.
+
+@item nntp-authinfo-function
+@vindex nntp-authinfo-function
+@findex nntp-send-authinfo
+@vindex nntp-authinfo-file
+This function will be used to send @samp{AUTHINFO} to the @acronym{NNTP}
+server. The default function is @code{nntp-send-authinfo}, which looks
+through your @file{~/.authinfo} (or whatever you've set the
+@code{nntp-authinfo-file} variable to) for applicable entries. If none
+are found, it will prompt you for a login name and a password. The
+format of the @file{~/.authinfo} file is (almost) the same as the
+@code{ftp} @file{~/.netrc} file, which is defined in the @code{ftp}
+manual page, but here are the salient facts:
+
+@enumerate
+@item
+The file contains one or more line, each of which define one server.
+
+@item
+Each line may contain an arbitrary number of token/value pairs.
+
+The valid tokens include @samp{machine}, @samp{login}, @samp{password},
+@samp{default}. In addition Gnus introduces two new tokens, not present
+in the original @file{.netrc}/@code{ftp} syntax, namely @samp{port} and
+@samp{force}. (This is the only way the @file{.authinfo} file format
+deviates from the @file{.netrc} file format.) @samp{port} is used to
+indicate what port on the server the credentials apply to and
+@samp{force} is explained below.
+
+@end enumerate
+
+Here's an example file:
+
+@example
+machine news.uio.no login larsi password geheimnis
+machine nntp.ifi.uio.no login larsi force yes
+@end example
+
+The token/value pairs may appear in any order; @samp{machine} doesn't
+have to be first, for instance.
+
+In this example, both login name and password have been supplied for the
+former server, while the latter has only the login name listed, and the
+user will be prompted for the password. The latter also has the
+@samp{force} tag, which means that the authinfo will be sent to the
+@var{nntp} server upon connection; the default (i.e., when there is not
+@samp{force} tag) is to not send authinfo to the @var{nntp} server
+until the @var{nntp} server asks for it.
+
+You can also add @samp{default} lines that will apply to all servers
+that don't have matching @samp{machine} lines.
+
+@example
+default force yes
+@end example
+
+This will force sending @samp{AUTHINFO} commands to all servers not
+previously mentioned.
+
+Remember to not leave the @file{~/.authinfo} file world-readable.
+
+@item nntp-server-action-alist
+@vindex nntp-server-action-alist
+This is a list of regexps to match on server types and actions to be
+taken when matches are made. For instance, if you want Gnus to beep
+every time you connect to innd, you could say something like:
+
+@lisp
+(setq nntp-server-action-alist
+ '(("innd" (ding))))
+@end lisp
+
+You probably don't want to do that, though.
+
+The default value is
+
+@lisp
+'(("nntpd 1\\.5\\.11t"
+ (remove-hook 'nntp-server-opened-hook
+ 'nntp-send-mode-reader)))
+@end lisp
+
+This ensures that Gnus doesn't send the @code{MODE READER} command to
+nntpd 1.5.11t, since that command chokes that server, I've been told.
+
+@item nntp-maximum-request
+@vindex nntp-maximum-request
+If the @acronym{NNTP} server doesn't support @acronym{NOV} headers, this back end
+will collect headers by sending a series of @code{head} commands. To
+speed things up, the back end sends lots of these commands without
+waiting for reply, and then reads all the replies. This is controlled
+by the @code{nntp-maximum-request} variable, and is 400 by default. If
+your network is buggy, you should set this to 1.
+
+@item nntp-connection-timeout
+@vindex nntp-connection-timeout
+If you have lots of foreign @code{nntp} groups that you connect to
+regularly, you're sure to have problems with @acronym{NNTP} servers not
+responding properly, or being too loaded to reply within reasonable
+time. This is can lead to awkward problems, which can be helped
+somewhat by setting @code{nntp-connection-timeout}. This is an integer
+that says how many seconds the @code{nntp} back end should wait for a
+connection before giving up. If it is @code{nil}, which is the default,
+no timeouts are done.
+
+@item nntp-nov-is-evil
+@vindex nntp-nov-is-evil
+If the @acronym{NNTP} server does not support @acronym{NOV}, you could set this
+variable to @code{t}, but @code{nntp} usually checks automatically whether @acronym{NOV}
+can be used.
+
+@item nntp-xover-commands
+@vindex nntp-xover-commands
+@cindex @acronym{NOV}
+@cindex XOVER
+List of strings used as commands to fetch @acronym{NOV} lines from a
+server. The default value of this variable is @code{("XOVER"
+"XOVERVIEW")}.
+
+@item nntp-nov-gap
+@vindex nntp-nov-gap
+@code{nntp} normally sends just one big request for @acronym{NOV} lines to
+the server. The server responds with one huge list of lines. However,
+if you have read articles 2--5000 in the group, and only want to read
+article 1 and 5001, that means that @code{nntp} will fetch 4999 @acronym{NOV}
+lines that you will not need. This variable says how
+big a gap between two consecutive articles is allowed to be before the
+@code{XOVER} request is split into several request. Note that if your
+network is fast, setting this variable to a really small number means
+that fetching will probably be slower. If this variable is @code{nil},
+@code{nntp} will never split requests. The default is 5.
+
+@item nntp-xref-number-is-evil
+@vindex nntp-xref-number-is-evil
+When Gnus refers to an article having the @code{Message-ID} that a user
+specifies or having the @code{Message-ID} of the parent article of the
+current one (@pxref{Finding the Parent}), Gnus sends a @code{HEAD}
+command to the @acronym{NNTP} server to know where it is, and the server
+returns the data containing the pairs of a group and an article number
+in the @code{Xref} header. Gnus normally uses the article number to
+refer to the article if the data shows that that article is in the
+current group, while it uses the @code{Message-ID} otherwise. However,
+some news servers, e.g., ones running Diablo, run multiple engines
+having the same articles but article numbers are not kept synchronized
+between them. In that case, the article number that appears in the
+@code{Xref} header varies by which engine is chosen, so you cannot refer
+to the parent article that is in the current group, for instance. If
+you connect to such a server, set this variable to a non-@code{nil}
+value, and Gnus never uses article numbers. For example:
+
+@lisp
+(setq gnus-select-method
+ '(nntp "newszilla"
+ (nntp-address "newszilla.example.com")
+ (nntp-xref-number-is-evil t)
+ @dots{}))
+@end lisp
+
+The default value of this server variable is @code{nil}.
+
+@item nntp-prepare-server-hook
+@vindex nntp-prepare-server-hook
+A hook run before attempting to connect to an @acronym{NNTP} server.
+
+@item nntp-record-commands
+@vindex nntp-record-commands
+If non-@code{nil}, @code{nntp} will log all commands it sends to the
+@acronym{NNTP} server (along with a timestamp) in the @file{*nntp-log*}
+buffer. This is useful if you are debugging a Gnus/@acronym{NNTP} connection
+that doesn't seem to work.
+
+@item nntp-open-connection-function
+@vindex nntp-open-connection-function
+It is possible to customize how the connection to the nntp server will
+be opened. If you specify an @code{nntp-open-connection-function}
+parameter, Gnus will use that function to establish the connection.
+Seven pre-made functions are supplied. These functions can be grouped
+in two categories: direct connection functions (four pre-made), and
+indirect ones (three pre-made).
+
+@item nntp-never-echoes-commands
+@vindex nntp-never-echoes-commands
+Non-@code{nil} means the nntp server never echoes commands. It is
+reported that some nntps server doesn't echo commands. So, you may want
+to set this to non-@code{nil} in the method for such a server setting
+@code{nntp-open-connection-function} to @code{nntp-open-ssl-stream} for
+example. The default value is @code{nil}. Note that the
+@code{nntp-open-connection-functions-never-echo-commands} variable
+overrides the @code{nil} value of this variable.
+
+@item nntp-open-connection-functions-never-echo-commands
+@vindex nntp-open-connection-functions-never-echo-commands
+List of functions that never echo commands. Add or set a function which
+you set to @code{nntp-open-connection-function} to this list if it does
+not echo commands. Note that a non-@code{nil} value of the
+@code{nntp-never-echoes-commands} variable overrides this variable. The
+default value is @code{(nntp-open-network-stream)}.
+
+@item nntp-prepare-post-hook
+@vindex nntp-prepare-post-hook
+A hook run just before posting an article. If there is no
+@code{Message-ID} header in the article and the news server provides the
+recommended ID, it will be added to the article before running this
+hook. It is useful to make @code{Cancel-Lock} headers even if you
+inhibit Gnus to add a @code{Message-ID} header, you could say:
+
+@lisp
+(add-hook 'nntp-prepare-post-hook 'canlock-insert-header)
+@end lisp
+
+Note that not all servers support the recommended ID@. This works for
+INN versions 2.3.0 and later, for instance.
+
+@item nntp-server-list-active-group
+If @code{nil}, then always use @samp{GROUP} instead of @samp{LIST
+ACTIVE}. This is usually slower, but on misconfigured servers that
+don't update their active files often, this can help.
+
+
+@end table
+
+@menu
+* Direct Functions:: Connecting directly to the server.
+* Indirect Functions:: Connecting indirectly to the server.
+* Common Variables:: Understood by several connection functions.
+@end menu
+
+
+@node Direct Functions
+@subsubsection Direct Functions
+@cindex direct connection functions
+
+These functions are called direct because they open a direct connection
+between your machine and the @acronym{NNTP} server. The behavior of these
+functions is also affected by commonly understood variables
+(@pxref{Common Variables}).
+
+@table @code
+@findex nntp-open-network-stream
+@item nntp-open-network-stream
+This is the default, and simply connects to some port or other on the
+remote system. If both Emacs and the server supports it, the
+connection will be upgraded to an encrypted @acronym{STARTTLS}
+connection automatically.
+
+@item network-only
+The same as the above, but don't do automatic @acronym{STARTTLS} upgrades.
+
+@findex nntp-open-tls-stream
+@item nntp-open-tls-stream
+Opens a connection to a server over a @dfn{secure} channel. To use
+this you must have @uref{http://www.gnu.org/software/gnutls/, GnuTLS}
+installed. You then define a server as follows:
+
+@lisp
+;; @r{"nntps" is port 563 and is predefined in our @file{/etc/services}}
+;; @r{however, @samp{gnutls-cli -p} doesn't like named ports.}
+;;
+(nntp "snews.bar.com"
+ (nntp-open-connection-function nntp-open-tls-stream)
+ (nntp-port-number 563)
+ (nntp-address "snews.bar.com"))
+@end lisp
+
+@findex nntp-open-ssl-stream
+@item nntp-open-ssl-stream
+Opens a connection to a server over a @dfn{secure} channel. To use
+this you must have @uref{http://www.openssl.org, OpenSSL}
+@ignore
+@c Defunct URL, ancient package, so don't mention it.
+or @uref{ftp://ftp.psy.uq.oz.au/pub/Crypto/SSL, SSLeay}
+@end ignore
+installed. You then define a server as follows:
+
+@lisp
+;; @r{"snews" is port 563 and is predefined in our @file{/etc/services}}
+;; @r{however, @samp{openssl s_client -port} doesn't like named ports.}
+;;
+(nntp "snews.bar.com"
+ (nntp-open-connection-function nntp-open-ssl-stream)
+ (nntp-port-number 563)
+ (nntp-address "snews.bar.com"))
+@end lisp
+
+@findex nntp-open-netcat-stream
+@item nntp-open-netcat-stream
+Opens a connection to an @acronym{NNTP} server using the @code{netcat}
+program. You might wonder why this function exists, since we have
+the default @code{nntp-open-network-stream} which would do the job. (One
+of) the reason(s) is that if you are behind a firewall but have direct
+connections to the outside world thanks to a command wrapper like
+@code{runsocks}, you can use it like this:
+
+@lisp
+(nntp "socksified"
+ (nntp-pre-command "runsocks")
+ (nntp-open-connection-function nntp-open-netcat-stream)
+ (nntp-address "the.news.server"))
+@end lisp
+
+With the default method, you would need to wrap your whole Emacs
+session, which is not a good idea.
+
+@findex nntp-open-telnet-stream
+@item nntp-open-telnet-stream
+Like @code{nntp-open-netcat-stream}, but uses @code{telnet} rather than
+@code{netcat}. @code{telnet} is a bit less robust because of things
+like line-end-conversion, but sometimes netcat is simply
+not available. The previous example would turn into:
+
+@lisp
+(nntp "socksified"
+ (nntp-pre-command "runsocks")
+ (nntp-open-connection-function nntp-open-telnet-stream)
+ (nntp-address "the.news.server")
+ (nntp-end-of-line "\n"))
+@end lisp
+@end table
+
+
+@node Indirect Functions
+@subsubsection Indirect Functions
+@cindex indirect connection functions
+
+These functions are called indirect because they connect to an
+intermediate host before actually connecting to the @acronym{NNTP} server.
+All of these functions and related variables are also said to belong to
+the ``via'' family of connection: they're all prefixed with ``via'' to make
+things cleaner. The behavior of these functions is also affected by
+commonly understood variables (@pxref{Common Variables}).
+
+@table @code
+@item nntp-open-via-rlogin-and-netcat
+@findex nntp-open-via-rlogin-and-netcat
+Does an @samp{rlogin} on a remote system, and then uses @code{netcat} to connect
+to the real @acronym{NNTP} server from there. This is useful for instance if
+you need to connect to a firewall machine first.
+
+@code{nntp-open-via-rlogin-and-netcat}-specific variables:
+
+@table @code
+@item nntp-via-rlogin-command
+@vindex nntp-via-rlogin-command
+Command used to log in on the intermediate host. The default is
+@samp{rsh}, but @samp{ssh} is a popular alternative.
+
+@item nntp-via-rlogin-command-switches
+@vindex nntp-via-rlogin-command-switches
+List of strings to be used as the switches to
+@code{nntp-via-rlogin-command}. The default is @code{nil}. If you use
+@samp{ssh} for @code{nntp-via-rlogin-command}, you may set this to
+@samp{("-C")} in order to compress all data connections.
+@end table
+
+@item nntp-open-via-rlogin-and-telnet
+@findex nntp-open-via-rlogin-and-telnet
+Does essentially the same, but uses @code{telnet} instead of @samp{netcat}
+to connect to the real @acronym{NNTP} server from the intermediate host.
+@code{telnet} is a bit less robust because of things like
+line-end-conversion, but sometimes @code{netcat} is simply not available.
+
+@code{nntp-open-via-rlogin-and-telnet}-specific variables:
+
+@table @code
+@item nntp-telnet-command
+@vindex nntp-telnet-command
+Command used to connect to the real @acronym{NNTP} server from the
+intermediate host. The default is @samp{telnet}.
+
+@item nntp-telnet-switches
+@vindex nntp-telnet-switches
+List of strings to be used as the switches to the
+@code{nntp-telnet-command} command. The default is @code{("-8")}.
+
+@item nntp-via-rlogin-command
+@vindex nntp-via-rlogin-command
+Command used to log in on the intermediate host. The default is
+@samp{rsh}, but @samp{ssh} is a popular alternative.
+
+@item nntp-via-rlogin-command-switches
+@vindex nntp-via-rlogin-command-switches
+List of strings to be used as the switches to
+@code{nntp-via-rlogin-command}. If you use @samp{ssh}, you may need to set
+this to @samp{("-t" "-e" "none")} or @samp{("-C" "-t" "-e" "none")} if
+the telnet command requires a pseudo-tty allocation on an intermediate
+host. The default is @code{nil}.
+@end table
+
+Note that you may want to change the value for @code{nntp-end-of-line}
+to @samp{\n} (@pxref{Common Variables}).
+
+@item nntp-open-via-telnet-and-telnet
+@findex nntp-open-via-telnet-and-telnet
+Does essentially the same, but uses @samp{telnet} instead of
+@samp{rlogin} to connect to the intermediate host.
+
+@code{nntp-open-via-telnet-and-telnet}-specific variables:
+
+@table @code
+@item nntp-via-telnet-command
+@vindex nntp-via-telnet-command
+Command used to @code{telnet} the intermediate host. The default is
+@samp{telnet}.
+
+@item nntp-via-telnet-switches
+@vindex nntp-via-telnet-switches
+List of strings to be used as the switches to the
+@code{nntp-via-telnet-command} command. The default is @samp{("-8")}.
+
+@item nntp-via-user-password
+@vindex nntp-via-user-password
+Password to use when logging in on the intermediate host.
+
+@item nntp-via-envuser
+@vindex nntp-via-envuser
+If non-@code{nil}, the intermediate @code{telnet} session (client and
+server both) will support the @code{ENVIRON} option and not prompt for
+login name. This works for Solaris @code{telnet}, for instance.
+
+@item nntp-via-shell-prompt
+@vindex nntp-via-shell-prompt
+Regexp matching the shell prompt on the intermediate host. The default
+is @samp{bash\\|\$ *\r?$\\|> *\r?}.
+
+@end table
+
+Note that you may want to change the value for @code{nntp-end-of-line}
+to @samp{\n} (@pxref{Common Variables}).
+@end table
+
+
+Here are some additional variables that are understood by all the above
+functions:
+
+@table @code
+
+@item nntp-via-user-name
+@vindex nntp-via-user-name
+User name to use when connecting to the intermediate host.
+
+@item nntp-via-address
+@vindex nntp-via-address
+Address of the intermediate host to connect to.
+
+@end table
+
+
+@node Common Variables
+@subsubsection Common Variables
+
+The following variables affect the behavior of all, or several of the
+pre-made connection functions. When not specified, all functions are
+affected (the values of the following variables will be used as the
+default if each virtual @code{nntp} server doesn't specify those server
+variables individually).
+
+@table @code
+
+@item nntp-pre-command
+@vindex nntp-pre-command
+A command wrapper to use when connecting through a non native
+connection function (all except @code{nntp-open-network-stream},
+@code{nntp-open-tls-stream}, and @code{nntp-open-ssl-stream}). This is
+where you would put a @samp{SOCKS} wrapper for instance.
+
+@item nntp-address
+@vindex nntp-address
+The address of the @acronym{NNTP} server.
+
+@item nntp-port-number
+@vindex nntp-port-number
+Port number to connect to the @acronym{NNTP} server. The default is
+@samp{nntp}. If you use @acronym{NNTP} over
+@acronym{TLS}/@acronym{SSL}, you may want to use integer ports rather
+than named ports (i.e., use @samp{563} instead of @samp{snews} or
+@samp{nntps}), because external @acronym{TLS}/@acronym{SSL} tools may
+not work with named ports.
+
+@item nntp-end-of-line
+@vindex nntp-end-of-line
+String to use as end-of-line marker when talking to the @acronym{NNTP}
+server. This is @samp{\r\n} by default, but should be @samp{\n} when
+using a non native telnet connection function.
+
+@item nntp-netcat-command
+@vindex nntp-netcat-command
+Command to use when connecting to the @acronym{NNTP} server through
+@samp{netcat}. This is @emph{not} for an intermediate host. This is
+just for the real @acronym{NNTP} server. The default is
+@samp{nc}.
+
+@item nntp-netcat-switches
+@vindex nntp-netcat-switches
+A list of switches to pass to @code{nntp-netcat-command}. The default
+is @samp{()}.
+
+@end table
+
+@node News Spool
+@subsection News Spool
+@cindex nnspool
+@cindex news spool
+
+Subscribing to a foreign group from the local spool is extremely easy,
+and might be useful, for instance, to speed up reading groups that
+contain very big articles---@samp{alt.binaries.pictures.furniture}, for
+instance.
+
+Anyway, you just specify @code{nnspool} as the method and @code{""} (or
+anything else) as the address.
+
+If you have access to a local spool, you should probably use that as the
+native select method (@pxref{Finding the News}). It is normally faster
+than using an @code{nntp} select method, but might not be. It depends.
+You just have to try to find out what's best at your site.
+
+@table @code
+
+@item nnspool-inews-program
+@vindex nnspool-inews-program
+Program used to post an article.
+
+@item nnspool-inews-switches
+@vindex nnspool-inews-switches
+Parameters given to the inews program when posting an article.
+
+@item nnspool-spool-directory
+@vindex nnspool-spool-directory
+Where @code{nnspool} looks for the articles. This is normally
+@file{/usr/spool/news/}.
+
+@item nnspool-nov-directory
+@vindex nnspool-nov-directory
+Where @code{nnspool} will look for @acronym{NOV} files. This is normally@*
+@file{/usr/spool/news/over.view/}.
+
+@item nnspool-lib-dir
+@vindex nnspool-lib-dir
+Where the news lib dir is (@file{/usr/lib/news/} by default).
+
+@item nnspool-active-file
+@vindex nnspool-active-file
+The name of the active file.
+
+@item nnspool-newsgroups-file
+@vindex nnspool-newsgroups-file
+The name of the group descriptions file.
+
+@item nnspool-history-file
+@vindex nnspool-history-file
+The name of the news history file.
+
+@item nnspool-active-times-file
+@vindex nnspool-active-times-file
+The name of the active date file.
+
+@item nnspool-nov-is-evil
+@vindex nnspool-nov-is-evil
+If non-@code{nil}, @code{nnspool} won't try to use any @acronym{NOV} files
+that it finds.
+
+@item nnspool-sift-nov-with-sed
+@vindex nnspool-sift-nov-with-sed
+@cindex sed
+If non-@code{nil}, which is the default, use @code{sed} to get the
+relevant portion from the overview file. If @code{nil},
+@code{nnspool} will load the entire file into a buffer and process it
+there.
+
+@end table
+
+
+@node Using IMAP
+@section Using IMAP
+@cindex imap
+
+The most popular mail backend is probably @code{nnimap}, which
+provides access to @acronym{IMAP} servers. @acronym{IMAP} servers
+store mail remotely, so the client doesn't store anything locally.
+This means that it's a convenient choice when you're reading your mail
+from different locations, or with different user agents.
+
+@menu
+* Connecting to an IMAP Server:: Getting started with @acronym{IMAP}.
+* Customizing the IMAP Connection:: Variables for @acronym{IMAP} connection.
+* Client-Side IMAP Splitting:: Put mail in the correct mail box.
+* Support for IMAP Extensions:: Getting extensions and labels from servers.
+@end menu
+
+
+@node Connecting to an IMAP Server
+@subsection Connecting to an IMAP Server
+
+Connecting to an @acronym{IMAP} can be very easy. Type @kbd{B} in the
+group buffer, or (if your primary interest is reading email), say
+something like:
+
+@example
+(setq gnus-select-method
+ '(nnimap "imap.gmail.com"))
+@end example
+
+You'll be prompted for a user name and password. If you grow tired of
+that, then add the following to your @file{~/.authinfo} file:
+
+@example
+machine imap.gmail.com login <username> password <password> port imap
+@end example
+
+That should basically be it for most users.
+
+
+@node Customizing the IMAP Connection
+@subsection Customizing the IMAP Connection
+
+Here's an example method that's more complex:
+
+@example
+(nnimap "imap.gmail.com"
+ (nnimap-inbox "INBOX")
+ (nnimap-split-methods default)
+ (nnimap-expunge t)
+ (nnimap-stream ssl))
+@end example
+
+@table @code
+@item nnimap-address
+The address of the server, like @samp{imap.gmail.com}.
+
+@item nnimap-server-port
+If the server uses a non-standard port, that can be specified here. A
+typical port would be @code{"imap"} or @code{"imaps"}.
+
+@item nnimap-stream
+How @code{nnimap} should connect to the server. Possible values are:
+
+@table @code
+@item undecided
+This is the default, and this first tries the @code{ssl} setting, and
+then tries the @code{network} setting.
+
+@item ssl
+This uses standard @acronym{TLS}/@acronym{SSL} connections.
+
+@item network
+Non-encrypted and unsafe straight socket connection, but will upgrade
+to encrypted @acronym{STARTTLS} if both Emacs and the server
+supports it.
+
+@item starttls
+Encrypted @acronym{STARTTLS} over the normal @acronym{IMAP} port.
+
+@item shell
+If you need to tunnel via other systems to connect to the server, you
+can use this option, and customize @code{nnimap-shell-program} to be
+what you need.
+
+@item plain
+Non-encrypted and unsafe straight socket connection.
+@acronym{STARTTLS} will not be used even if it is available.
+
+@end table
+
+@item nnimap-authenticator
+Some @acronym{IMAP} servers allow anonymous logins. In that case,
+this should be set to @code{anonymous}. If this variable isn't set,
+the normal login methods will be used. If you wish to specify a
+specific login method to be used, you can set this variable to either
+@code{login} (the traditional @acronym{IMAP} login method),
+@code{plain} or @code{cram-md5}.
+
+@item nnimap-expunge
+If non-@code{nil}, expunge articles after deleting them. This is always done
+if the server supports UID EXPUNGE, but it's not done by default on
+servers that doesn't support that command.
+
+@item nnimap-streaming
+Virtually all @acronym{IMAP} server support fast streaming of data.
+If you have problems connecting to the server, try setting this to
+@code{nil}.
+
+@item nnimap-fetch-partial-articles
+If non-@code{nil}, fetch partial articles from the server. If set to
+a string, then it's interpreted as a regexp, and parts that have
+matching types will be fetched. For instance, @samp{"text/"} will
+fetch all textual parts, while leaving the rest on the server.
+
+@item nnimap-record-commands
+If non-@code{nil}, record all @acronym{IMAP} commands in the
+@samp{"*imap log*"} buffer.
+
+@end table
+
+
+@node Client-Side IMAP Splitting
+@subsection Client-Side IMAP Splitting
+
+Many people prefer to do the sorting/splitting of mail into their mail
+boxes on the @acronym{IMAP} server. That way they don't have to
+download the mail they're not all that interested in.
+
+If you do want to do client-side mail splitting, then the following
+variables are relevant:
+
+@table @code
+@item nnimap-inbox
+This is the @acronym{IMAP} mail box that will be scanned for new
+mail. This can also be a list of mail box names.
+
+@item nnimap-split-methods
+Uses the same syntax as @code{nnmail-split-methods} (@pxref{Splitting
+Mail}), except the symbol @code{default}, which means that it should
+use the value of the @code{nnmail-split-methods} variable.
+
+@item nnimap-split-fancy
+Uses the same syntax as @code{nnmail-split-fancy}.
+
+@item nnimap-unsplittable-articles
+List of flag symbols to ignore when doing splitting. That is,
+articles that have these flags won't be considered when splitting.
+The default is @samp{(%Deleted %Seen)}.
+
+@end table
+
+Here's a complete example @code{nnimap} backend with a client-side
+``fancy'' splitting method:
+
+@example
+(nnimap "imap.example.com"
+ (nnimap-inbox "INBOX")
+ (nnimap-split-methods
+ (| ("MailScanner-SpamCheck" "spam" "spam.detected")
+ (to "foo@@bar.com" "foo")
+ "undecided")))
+@end example
+
+
+@node Support for IMAP Extensions
+@subsection Support for IMAP Extensions
+
+@cindex Gmail
+@cindex X-GM-LABELS
+@cindex IMAP labels
+
+If you're using Google's Gmail, you may want to see your Gmail labels
+when reading your mail. Gnus can give you this information if you ask
+for @samp{X-GM-LABELS} in the variable @code{gnus-extra-headers}. For
+example:
+
+@example
+(setq gnus-extra-headers
+ '(To Newsgroups X-GM-LABELS))
+@end example
+
+This will result in Gnus storing your labels in message header
+structures for later use. The content is always a parenthesized
+(possible empty) list.
+
+
+
+@node Getting Mail
+@section Getting Mail
+@cindex reading mail
+@cindex mail
+
+Reading mail with a newsreader---isn't that just plain WeIrD@? But of
+course.
+
+@menu
+* Mail in a Newsreader:: Important introductory notes.
+* Getting Started Reading Mail:: A simple cookbook example.
+* Splitting Mail:: How to create mail groups.
+* Mail Sources:: How to tell Gnus where to get mail from.
+* Mail Back End Variables:: Variables for customizing mail handling.
+* Fancy Mail Splitting:: Gnus can do hairy splitting of incoming mail.
+* Group Mail Splitting:: Use group customize to drive mail splitting.
+* Incorporating Old Mail:: What about the old mail you have?
+* Expiring Mail:: Getting rid of unwanted mail.
+* Washing Mail:: Removing cruft from the mail you get.
+* Duplicates:: Dealing with duplicated mail.
+* Not Reading Mail:: Using mail back ends for reading other files.
+* Choosing a Mail Back End:: Gnus can read a variety of mail formats.
+@end menu
+
+
+@node Mail in a Newsreader
+@subsection Mail in a Newsreader
+
+If you are used to traditional mail readers, but have decided to switch
+to reading mail with Gnus, you may find yourself experiencing something
+of a culture shock.
+
+Gnus does not behave like traditional mail readers. If you want to make
+it behave that way, you can, but it's an uphill battle.
+
+Gnus, by default, handles all its groups using the same approach. This
+approach is very newsreaderly---you enter a group, see the new/unread
+messages, and when you read the messages, they get marked as read, and
+you don't see them any more. (Unless you explicitly ask for them.)
+
+In particular, you do not do anything explicitly to delete messages.
+
+Does this mean that all the messages that have been marked as read are
+deleted? How awful!
+
+But, no, it means that old messages are @dfn{expired} according to some
+scheme or other. For news messages, the expire process is controlled by
+the news administrator; for mail, the expire process is controlled by
+you. The expire process for mail is covered in depth in @ref{Expiring
+Mail}.
+
+What many Gnus users find, after using it a while for both news and
+mail, is that the transport mechanism has very little to do with how
+they want to treat a message.
+
+Many people subscribe to several mailing lists. These are transported
+via @acronym{SMTP}, and are therefore mail. But we might go for weeks without
+answering, or even reading these messages very carefully. We may not
+need to save them because if we should need to read one again, they are
+archived somewhere else.
+
+Some people have local news groups which have only a handful of readers.
+These are transported via @acronym{NNTP}, and are therefore news. But we may need
+to read and answer a large fraction of the messages very carefully in
+order to do our work. And there may not be an archive, so we may need
+to save the interesting messages the same way we would personal mail.
+
+The important distinction turns out to be not the transport mechanism,
+but other factors such as how interested we are in the subject matter,
+or how easy it is to retrieve the message if we need to read it again.
+
+Gnus provides many options for sorting mail into ``groups'' which behave
+like newsgroups, and for treating each group (whether mail or news)
+differently.
+
+Some users never get comfortable using the Gnus (ahem) paradigm and wish
+that Gnus should grow up and be a male, er, mail reader. It is possible
+to whip Gnus into a more mailreaderly being, but, as said before, it's
+not easy. People who prefer proper mail readers should try @sc{vm}
+instead, which is an excellent, and proper, mail reader.
+
+I don't mean to scare anybody off, but I want to make it clear that you
+may be required to learn a new way of thinking about messages. After
+you've been subjected to The Gnus Way, you will come to love it. I can
+guarantee it. (At least the guy who sold me the Emacs Subliminal
+Brain-Washing Functions that I've put into Gnus did guarantee it. You
+Will Be Assimilated. You Love Gnus. You Love The Gnus Mail Way.
+You Do.)
+
+
+@node Getting Started Reading Mail
+@subsection Getting Started Reading Mail
+
+It's quite easy to use Gnus to read your new mail. You just plonk the
+mail back end of your choice into @code{gnus-secondary-select-methods},
+and things will happen automatically.
+
+For instance, if you want to use @code{nnml} (which is a ``one file per
+mail'' back end), you could put the following in your @file{~/.gnus.el} file:
+
+@lisp
+(setq gnus-secondary-select-methods '((nnml "")))
+@end lisp
+
+Now, the next time you start Gnus, this back end will be queried for new
+articles, and it will move all the messages in your spool file to its
+directory, which is @file{~/Mail/} by default. The new group that will
+be created (@samp{mail.misc}) will be subscribed, and you can read it
+like any other group.
+
+You will probably want to split the mail into several groups, though:
+
+@lisp
+(setq nnmail-split-methods
+ '(("junk" "^From:.*Lars Ingebrigtsen")
+ ("crazy" "^Subject:.*die\\|^Organization:.*flabby")
+ ("other" "")))
+@end lisp
+
+This will result in three new @code{nnml} mail groups being created:
+@samp{nnml:junk}, @samp{nnml:crazy}, and @samp{nnml:other}. All the
+mail that doesn't fit into the first two groups will be placed in the
+last group.
+
+This should be sufficient for reading mail with Gnus. You might want to
+give the other sections in this part of the manual a perusal, though.
+Especially @pxref{Choosing a Mail Back End} and @pxref{Expiring Mail}.
+
+
+@node Splitting Mail
+@subsection Splitting Mail
+@cindex splitting mail
+@cindex mail splitting
+@cindex mail filtering (splitting)
+
+@vindex nnmail-split-methods
+The @code{nnmail-split-methods} variable says how the incoming mail is
+to be split into groups.
+
+@lisp
+(setq nnmail-split-methods
+ '(("mail.junk" "^From:.*Lars Ingebrigtsen")
+ ("mail.crazy" "^Subject:.*die\\|^Organization:.*flabby")
+ ("mail.other" "")))
+@end lisp
+
+This variable is a list of lists, where the first element of each of
+these lists is the name of the mail group (they do not have to be called
+something beginning with @samp{mail}, by the way), and the second
+element is a regular expression used on the header of each mail to
+determine if it belongs in this mail group. The first string may
+contain @samp{\\1} forms, like the ones used by @code{replace-match} to
+insert sub-expressions from the matched text. For instance:
+
+@lisp
+("list.\\1" "From:.* \\(.*\\)-list@@majordomo.com")
+@end lisp
+
+@noindent
+In that case, @code{nnmail-split-lowercase-expanded} controls whether
+the inserted text should be made lowercase. @xref{Fancy Mail Splitting}.
+
+The second element can also be a function. In that case, it will be
+called narrowed to the headers with the first element of the rule as the
+argument. It should return a non-@code{nil} value if it thinks that the
+mail belongs in that group.
+
+@cindex @samp{bogus} group
+The last of these groups should always be a general one, and the regular
+expression should @emph{always} be @samp{""} so that it matches any mails
+that haven't been matched by any of the other regexps. (These rules are
+processed from the beginning of the alist toward the end. The first rule
+to make a match will ``win'', unless you have crossposting enabled. In
+that case, all matching rules will ``win''.) If no rule matched, the mail
+will end up in the @samp{bogus} group. When new groups are created by
+splitting mail, you may want to run @code{gnus-group-find-new-groups} to
+see the new groups. This also applies to the @samp{bogus} group.
+
+If you like to tinker with this yourself, you can set this variable to a
+function of your choice. This function will be called without any
+arguments in a buffer narrowed to the headers of an incoming mail
+message. The function should return a list of group names that it
+thinks should carry this mail message.
+
+This variable can also be a fancy split method. For the syntax,
+see @ref{Fancy Mail Splitting}.
+
+Note that the mail back ends are free to maul the poor, innocent,
+incoming headers all they want to. They all add @code{Lines} headers;
+some add @code{X-Gnus-Group} headers; most rename the Unix mbox
+@code{From<SPACE>} line to something else.
+
+@vindex nnmail-crosspost
+The mail back ends all support cross-posting. If several regexps match,
+the mail will be ``cross-posted'' to all those groups.
+@code{nnmail-crosspost} says whether to use this mechanism or not. Note
+that no articles are crossposted to the general (@samp{""}) group.
+
+@vindex nnmail-crosspost-link-function
+@cindex crosspost
+@cindex links
+@code{nnmh} and @code{nnml} makes crossposts by creating hard links to
+the crossposted articles. However, not all file systems support hard
+links. If that's the case for you, set
+@code{nnmail-crosspost-link-function} to @code{copy-file}. (This
+variable is @code{add-name-to-file} by default.)
+
+@kindex M-x nnmail-split-history
+@findex nnmail-split-history
+If you wish to see where the previous mail split put the messages, you
+can use the @kbd{M-x nnmail-split-history} command. If you wish to see
+where re-spooling messages would put the messages, you can use
+@code{gnus-summary-respool-trace} and related commands (@pxref{Mail
+Group Commands}).
+
+@vindex nnmail-split-header-length-limit
+Header lines longer than the value of
+@code{nnmail-split-header-length-limit} are excluded from the split
+function.
+
+@vindex nnmail-mail-splitting-decodes
+@vindex nnmail-mail-splitting-charset
+By default, splitting does not decode headers, so you can not match on
+non-@acronym{ASCII} strings. But it is useful if you want to match
+articles based on the raw header data. To enable it, set the
+@code{nnmail-mail-splitting-decodes} variable to a non-@code{nil} value.
+In addition, the value of the @code{nnmail-mail-splitting-charset}
+variable is used for decoding non-@acronym{MIME} encoded string when
+@code{nnmail-mail-splitting-decodes} is non-@code{nil}. The default
+value is @code{nil} which means not to decode non-@acronym{MIME} encoded
+string. A suitable value for you will be @code{undecided} or be the
+charset used normally in mails you are interested in.
+
+@vindex nnmail-resplit-incoming
+By default, splitting is performed on all incoming messages. If you
+specify a @code{directory} entry for the variable @code{mail-sources}
+(@pxref{Mail Source Specifiers}), however, then splitting does
+@emph{not} happen by default. You can set the variable
+@code{nnmail-resplit-incoming} to a non-@code{nil} value to make
+splitting happen even in this case. (This variable has no effect on
+other kinds of entries.)
+
+Gnus gives you all the opportunity you could possibly want for shooting
+yourself in the foot. Let's say you create a group that will contain
+all the mail you get from your boss. And then you accidentally
+unsubscribe from the group. Gnus will still put all the mail from your
+boss in the unsubscribed group, and so, when your boss mails you ``Have
+that report ready by Monday or you're fired!'', you'll never see it and,
+come Tuesday, you'll still believe that you're gainfully employed while
+you really should be out collecting empty bottles to save up for next
+month's rent money.
+
+
+@node Mail Sources
+@subsection Mail Sources
+
+Mail can be gotten from many different sources---the mail spool, from
+a @acronym{POP} mail server, from a procmail directory, or from a
+maildir, for instance.
+
+@menu
+* Mail Source Specifiers:: How to specify what a mail source is.
+* Mail Source Functions::
+* Mail Source Customization:: Some variables that influence things.
+* Fetching Mail:: Using the mail source specifiers.
+@end menu
+
+
+@node Mail Source Specifiers
+@subsubsection Mail Source Specifiers
+@cindex POP
+@cindex mail server
+@cindex procmail
+@cindex mail spool
+@cindex mail source
+
+You tell Gnus how to fetch mail by setting @code{mail-sources}
+(@pxref{Fetching Mail}) to a @dfn{mail source specifier}.
+
+Here's an example:
+
+@lisp
+(pop :server "pop3.mailserver.com" :user "myname")
+@end lisp
+
+As can be observed, a mail source specifier is a list where the first
+element is a @dfn{mail source type}, followed by an arbitrary number of
+@dfn{keywords}. Keywords that are not explicitly specified are given
+default values.
+
+The @code{mail-sources} is global for all mail groups. You can specify
+an additional mail source for a particular group by including the
+@code{group} mail specifier in @code{mail-sources}, and setting a
+@code{mail-source} group parameter (@pxref{Group Parameters}) specifying
+a single mail source. When this is used, @code{mail-sources} is
+typically just @code{(group)}; the @code{mail-source} parameter for a
+group might look like this:
+
+@lisp
+(mail-source . (file :path "home/user/spools/foo.spool"))
+@end lisp
+
+This means that the group's (and only this group's) messages will be
+fetched from the spool file @samp{/user/spools/foo.spool}.
+
+The following mail source types are available:
+
+@table @code
+@item file
+Get mail from a single file; typically from the mail spool.
+
+Keywords:
+
+@table @code
+@item :path
+The file name. Defaults to the value of the @env{MAIL}
+environment variable or the value of @code{rmail-spool-directory}
+(usually something like @file{/usr/mail/spool/user-name}).
+
+@item :prescript
+@itemx :postscript
+Script run before/after fetching mail.
+@end table
+
+An example file mail source:
+
+@lisp
+(file :path "/usr/spool/mail/user-name")
+@end lisp
+
+Or using the default file name:
+
+@lisp
+(file)
+@end lisp
+
+If the mail spool file is not located on the local machine, it's best
+to use @acronym{POP} or @acronym{IMAP} or the like to fetch the mail.
+You can not use ange-ftp file names here---it has no way to lock the
+mail spool while moving the mail.
+
+If it's impossible to set up a proper server, you can use ssh instead.
+
+@lisp
+(setq mail-sources
+ '((file :prescript "ssh host bin/getmail >%t")))
+@end lisp
+
+The @samp{getmail} script would look something like the following:
+
+@example
+#!/bin/sh
+# getmail - move mail from spool to stdout
+# flu@@iki.fi
+
+MOVEMAIL=/usr/lib/emacs/20.3/i386-redhat-linux/movemail
+TMP=$HOME/Mail/tmp
+rm -f $TMP; $MOVEMAIL $MAIL $TMP >/dev/null && cat $TMP
+@end example
+
+Alter this script to fit the @samp{movemail} and temporary
+file you want to use.
+
+
+@item directory
+@vindex nnmail-scan-directory-mail-source-once
+Get mail from several files in a directory. This is typically used
+when you have procmail split the incoming mail into several files.
+That is, there is a one-to-one correspondence between files in that
+directory and groups, so that mail from the file @file{foo.bar.spool}
+will be put in the group @code{foo.bar}. (You can change the suffix
+to be used instead of @code{.spool}.) Setting
+@code{nnmail-scan-directory-mail-source-once} to non-@code{nil} forces
+Gnus to scan the mail source only once. This is particularly useful
+if you want to scan mail groups at a specified level.
+
+@vindex nnmail-resplit-incoming
+There is also the variable @code{nnmail-resplit-incoming}, if you set
+that to a non-@code{nil} value, then the normal splitting process is
+applied to all the files from the directory, @ref{Splitting Mail}.
+
+Keywords:
+
+@table @code
+@item :path
+The name of the directory where the files are. There is no default
+value.
+
+@item :suffix
+Only files ending with this suffix are used. The default is
+@samp{.spool}.
+
+@item :predicate
+Only files that have this predicate return non-@code{nil} are returned.
+The default is @code{identity}. This is used as an additional
+filter---only files that have the right suffix @emph{and} satisfy this
+predicate are considered.
+
+@item :prescript
+@itemx :postscript
+Script run before/after fetching mail.
+
+@end table
+
+An example directory mail source:
+
+@lisp
+(directory :path "/home/user-name/procmail-dir/"
+ :suffix ".prcml")
+@end lisp
+
+@item pop
+Get mail from a @acronym{POP} server.
+
+Keywords:
+
+@table @code
+@item :server
+The name of the @acronym{POP} server. The default is taken from the
+@env{MAILHOST} environment variable.
+
+@item :port
+The port number of the @acronym{POP} server. This can be a number (e.g.,
+@samp{:port 1234}) or a string (e.g., @samp{:port "pop3"}). If it is a
+string, it should be a service name as listed in @file{/etc/services} on
+Unix systems. The default is @samp{"pop3"}. On some systems you might
+need to specify it as @samp{"pop-3"} instead.
+
+@item :user
+The user name to give to the @acronym{POP} server. The default is the login
+name.
+
+@item :password
+The password to give to the @acronym{POP} server. If not specified,
+the user is prompted.
+
+@item :program
+The program to use to fetch mail from the @acronym{POP} server. This
+should be a @code{format}-like string. Here's an example:
+
+@example
+fetchmail %u@@%s -P %p %t
+@end example
+
+The valid format specifier characters are:
+
+@table @samp
+@item t
+The name of the file the mail is to be moved to. This must always be
+included in this string.
+
+@item s
+The name of the server.
+
+@item P
+The port number of the server.
+
+@item u
+The user name to use.
+
+@item p
+The password to use.
+@end table
+
+The values used for these specs are taken from the values you give the
+corresponding keywords.
+
+@item :prescript
+A script to be run before fetching the mail. The syntax is the same as
+the @code{:program} keyword. This can also be a function to be run.
+
+One popular way to use this is to set up an SSH tunnel to access the
+@acronym{POP} server. Here's an example:
+
+@lisp
+(pop :server "127.0.0.1"
+ :port 1234
+ :user "foo"
+ :password "secret"
+ :prescript
+ "nohup ssh -f -L 1234:pop.server:110 remote.host sleep 3600 &")
+@end lisp
+
+@item :postscript
+A script to be run after fetching the mail. The syntax is the same as
+the @code{:program} keyword. This can also be a function to be run.
+
+@item :function
+The function to use to fetch mail from the @acronym{POP} server. The
+function is called with one parameter---the name of the file where the
+mail should be moved to.
+
+@item :authentication
+This can be either the symbol @code{password} or the symbol @code{apop}
+and says what authentication scheme to use. The default is
+@code{password}.
+
+@item :leave
+Non-@code{nil} if the mail is to be left on the @acronym{POP} server
+after fetching. Only the built-in @code{pop3-movemail} program (the
+default) supports this keyword.
+
+If this is a number, leave mails on the server for this many days since
+you first checked new mails. In that case, mails once fetched will
+never be fetched again by the @acronym{UIDL} control. If this is
+@code{nil} (the default), mails will be deleted on the server right
+after fetching. If this is neither @code{nil} nor a number, all mails
+will be left on the server, and you will end up getting the same mails
+again and again.
+
+@vindex pop3-uidl-file
+The @code{pop3-uidl-file} variable specifies the file to which the
+@acronym{UIDL} data are locally stored. The default value is
+@file{~/.pop3-uidl}.
+
+Note that @acronym{POP} servers maintain no state information between
+sessions, so what the client believes is there and what is actually
+there may not match up. If they do not, then you may get duplicate
+mails or the whole thing can fall apart and leave you with a corrupt
+mailbox.
+
+@end table
+
+@findex pop3-movemail
+@vindex pop3-leave-mail-on-server
+If the @code{:program} and @code{:function} keywords aren't specified,
+@code{pop3-movemail} will be used.
+
+Here are some examples for getting mail from a @acronym{POP} server.
+
+Fetch from the default @acronym{POP} server, using the default user
+name, and default fetcher:
+
+@lisp
+(pop)
+@end lisp
+
+Fetch from a named server with a named user and password:
+
+@lisp
+(pop :server "my.pop.server"
+ :user "user-name" :password "secret")
+@end lisp
+
+Leave mails on the server for 14 days:
+
+@lisp
+(pop :server "my.pop.server"
+ :user "user-name" :password "secret"
+ :leave 14)
+@end lisp
+
+Use @samp{movemail} to move the mail:
+
+@lisp
+(pop :program "movemail po:%u %t %p")
+@end lisp
+
+@item maildir
+Get mail from a maildir. This is a type of mailbox that is supported by
+at least qmail and postfix, where each file in a special directory
+contains exactly one mail.
+
+Keywords:
+
+@table @code
+@item :path
+The name of the directory where the mails are stored. The default is
+taken from the @env{MAILDIR} environment variable or
+@file{~/Maildir/}.
+@item :subdirs
+The subdirectories of the Maildir. The default is
+@samp{("new" "cur")}.
+
+@c If you sometimes look at your mail through a pop3 daemon before fetching
+@c them with Gnus, you may also have to fetch your mails from the
+@c @code{cur} directory inside the maildir, like in the first example
+@c below.
+
+You can also get mails from remote hosts (because maildirs don't suffer
+from locking problems).
+
+@end table
+
+Two example maildir mail sources:
+
+@lisp
+(maildir :path "/home/user-name/Maildir/"
+ :subdirs ("cur" "new"))
+@end lisp
+
+@lisp
+(maildir :path "/user@@remotehost.org:~/Maildir/"
+ :subdirs ("new"))
+@end lisp
+
+@item imap
+Get mail from a @acronym{IMAP} server. If you don't want to use
+@acronym{IMAP} as intended, as a network mail reading protocol (i.e.,
+with nnimap), for some reason or other, Gnus let you treat it similar
+to a @acronym{POP} server and fetches articles from a given
+@acronym{IMAP} mailbox. @xref{Using IMAP}, for more information.
+
+Keywords:
+
+@table @code
+@item :server
+The name of the @acronym{IMAP} server. The default is taken from the
+@env{MAILHOST} environment variable.
+
+@item :port
+The port number of the @acronym{IMAP} server. The default is @samp{143}, or
+@samp{993} for @acronym{TLS}/@acronym{SSL} connections.
+
+@item :user
+The user name to give to the @acronym{IMAP} server. The default is the login
+name.
+
+@item :password
+The password to give to the @acronym{IMAP} server. If not specified, the user is
+prompted.
+
+@item :stream
+What stream to use for connecting to the server, this is one of the
+symbols in @code{imap-stream-alist}. Right now, this means
+@samp{gssapi}, @samp{kerberos4}, @samp{starttls}, @samp{tls},
+@samp{ssl}, @samp{shell} or the default @samp{network}.
+
+@item :authentication
+Which authenticator to use for authenticating to the server, this is
+one of the symbols in @code{imap-authenticator-alist}. Right now,
+this means @samp{gssapi}, @samp{kerberos4}, @samp{digest-md5},
+@samp{cram-md5}, @samp{anonymous} or the default @samp{login}.
+
+@item :program
+When using the @samp{shell} :stream, the contents of this variable is
+mapped into the @code{imap-shell-program} variable. This should be a
+@code{format}-like string (or list of strings). Here's an example:
+
+@example
+ssh %s imapd
+@end example
+
+Make sure nothing is interfering with the output of the program, e.g.,
+don't forget to redirect the error output to the void. The valid format
+specifier characters are:
+
+@table @samp
+@item s
+The name of the server.
+
+@item l
+User name from @code{imap-default-user}.
+
+@item p
+The port number of the server.
+@end table
+
+The values used for these specs are taken from the values you give the
+corresponding keywords.
+
+@item :mailbox
+The name of the mailbox to get mail from. The default is @samp{INBOX}
+which normally is the mailbox which receives incoming mail. Instead of
+a single mailbox, this can be a list of mailboxes to fetch mail from.
+
+@item :predicate
+The predicate used to find articles to fetch. The default, @samp{UNSEEN
+UNDELETED}, is probably the best choice for most people, but if you
+sometimes peek in your mailbox with a @acronym{IMAP} client and mark some
+articles as read (or; SEEN) you might want to set this to @samp{1:*}.
+Then all articles in the mailbox is fetched, no matter what. For a
+complete list of predicates, see RFC 2060 section 6.4.4.
+
+@item :fetchflag
+How to flag fetched articles on the server, the default @samp{\Deleted}
+will mark them as deleted, an alternative would be @samp{\Seen} which
+would simply mark them as read. These are the two most likely choices,
+but more flags are defined in RFC 2060 section 2.3.2.
+
+@item :dontexpunge
+If non-@code{nil}, don't remove all articles marked as deleted in the
+mailbox after finishing the fetch.
+
+@end table
+
+An example @acronym{IMAP} mail source:
+
+@lisp
+(imap :server "mail.mycorp.com"
+ :stream kerberos4
+ :fetchflag "\\Seen")
+@end lisp
+
+@item group
+Get the actual mail source from the @code{mail-source} group parameter,
+@xref{Group Parameters}.
+
+@end table
+
+@table @dfn
+@item Common Keywords
+Common keywords can be used in any type of mail source.
+
+Keywords:
+
+@table @code
+@item :plugged
+If non-@code{nil}, fetch the mail even when Gnus is unplugged. If you
+use directory source to get mail, you can specify it as in this
+example:
+
+@lisp
+(setq mail-sources
+ '((directory :path "/home/pavel/.Spool/"
+ :suffix ""
+ :plugged t)))
+@end lisp
+
+Gnus will then fetch your mail even when you are unplugged. This is
+useful when you use local mail and news.
+
+@end table
+@end table
+
+@node Mail Source Functions
+@subsubsection Function Interface
+
+Some of the above keywords specify a Lisp function to be executed.
+For each keyword @code{:foo}, the Lisp variable @code{foo} is bound to
+the value of the keyword while the function is executing. For example,
+consider the following mail-source setting:
+
+@lisp
+(setq mail-sources '((pop :user "jrl"
+ :server "pophost" :function fetchfunc)))
+@end lisp
+
+While the function @code{fetchfunc} is executing, the symbol @code{user}
+is bound to @code{"jrl"}, and the symbol @code{server} is bound to
+@code{"pophost"}. The symbols @code{port}, @code{password},
+@code{program}, @code{prescript}, @code{postscript}, @code{function},
+and @code{authentication} are also bound (to their default values).
+
+See above for a list of keywords for each type of mail source.
+
+
+@node Mail Source Customization
+@subsubsection Mail Source Customization
+
+The following is a list of variables that influence how the mail is
+fetched. You would normally not need to set or change any of these
+variables.
+
+@table @code
+@item mail-source-crash-box
+@vindex mail-source-crash-box
+File where mail will be stored while processing it. The default is@*
+@file{~/.emacs-mail-crash-box}.
+
+@cindex Incoming*
+@item mail-source-delete-incoming
+@vindex mail-source-delete-incoming
+If non-@code{nil}, delete incoming files after handling them. If
+@code{t}, delete the files immediately, if @code{nil}, never delete any
+files. If a positive number, delete files older than number of days
+(the deletion will only happen when receiving new mail). You may also
+set @code{mail-source-delete-incoming} to @code{nil} and call
+@code{mail-source-delete-old-incoming} from a hook or interactively.
+@code{mail-source-delete-incoming} defaults to @code{10} in alpha Gnusae
+and @code{2} in released Gnusae. @xref{Gnus Development}.
+
+@item mail-source-delete-old-incoming-confirm
+@vindex mail-source-delete-old-incoming-confirm
+If non-@code{nil}, ask for confirmation before deleting old incoming
+files. This variable only applies when
+@code{mail-source-delete-incoming} is a positive number.
+
+@item mail-source-ignore-errors
+@vindex mail-source-ignore-errors
+If non-@code{nil}, ignore errors when reading mail from a mail source.
+
+@item mail-source-directory
+@vindex mail-source-directory
+Directory where incoming mail source files (if any) will be stored. The
+default is @file{~/Mail/}. At present, the only thing this is used for
+is to say where the incoming files will be stored if the variable
+@code{mail-source-delete-incoming} is @code{nil} or a number.
+
+@item mail-source-incoming-file-prefix
+@vindex mail-source-incoming-file-prefix
+Prefix for file name for storing incoming mail. The default is
+@file{Incoming}, in which case files will end up with names like
+@file{Incoming30630D_} or @file{Incoming298602ZD}. This is really only
+relevant if @code{mail-source-delete-incoming} is @code{nil} or a
+number.
+
+@item mail-source-default-file-modes
+@vindex mail-source-default-file-modes
+All new mail files will get this file mode. The default is @code{#o600}.
+
+@item mail-source-movemail-program
+@vindex mail-source-movemail-program
+If non-@code{nil}, name of program for fetching new mail. If
+@code{nil}, @code{movemail} in @var{exec-directory}.
+
+@end table
+
+
+@node Fetching Mail
+@subsubsection Fetching Mail
+
+@vindex mail-sources
+The way to actually tell Gnus where to get new mail from is to set
+@code{mail-sources} to a list of mail source specifiers
+(@pxref{Mail Source Specifiers}).
+
+If this variable is @code{nil}, the mail back ends will never attempt to
+fetch mail by themselves.
+
+If you want to fetch mail both from your local spool as well as a
+@acronym{POP} mail server, you'd say something like:
+
+@lisp
+(setq mail-sources
+ '((file)
+ (pop :server "pop3.mail.server"
+ :password "secret")))
+@end lisp
+
+Or, if you don't want to use any of the keyword defaults:
+
+@lisp
+(setq mail-sources
+ '((file :path "/var/spool/mail/user-name")
+ (pop :server "pop3.mail.server"
+ :user "user-name"
+ :port "pop3"
+ :password "secret")))
+@end lisp
+
+
+When you use a mail back end, Gnus will slurp all your mail from your
+inbox and plonk it down in your home directory. Gnus doesn't move any
+mail if you're not using a mail back end---you have to do a lot of magic
+invocations first. At the time when you have finished drawing the
+pentagram, lightened the candles, and sacrificed the goat, you really
+shouldn't be too surprised when Gnus moves your mail.
+
+
+
+@node Mail Back End Variables
+@subsection Mail Back End Variables
+
+These variables are (for the most part) pertinent to all the various
+mail back ends.
+
+@table @code
+@vindex nnmail-read-incoming-hook
+@item nnmail-read-incoming-hook
+The mail back ends all call this hook after reading new mail. You can
+use this hook to notify any mail watch programs, if you want to.
+
+@vindex nnmail-split-hook
+@item nnmail-split-hook
+@findex gnus-article-decode-encoded-words
+@cindex RFC 1522 decoding
+@cindex RFC 2047 decoding
+Hook run in the buffer where the mail headers of each message is kept
+just before the splitting based on these headers is done. The hook is
+free to modify the buffer contents in any way it sees fit---the buffer
+is discarded after the splitting has been done, and no changes performed
+in the buffer will show up in any files.
+@code{gnus-article-decode-encoded-words} is one likely function to add
+to this hook.
+
+@vindex nnmail-pre-get-new-mail-hook
+@vindex nnmail-post-get-new-mail-hook
+@item nnmail-pre-get-new-mail-hook
+@itemx nnmail-post-get-new-mail-hook
+These are two useful hooks executed when treating new incoming
+mail---@code{nnmail-pre-get-new-mail-hook} (is called just before
+starting to handle the new mail) and
+@code{nnmail-post-get-new-mail-hook} (is called when the mail handling
+is done). Here's and example of using these two hooks to change the
+default file modes the new mail files get:
+
+@lisp
+(add-hook 'nnmail-pre-get-new-mail-hook
+ (lambda () (set-default-file-modes #o700)))
+
+(add-hook 'nnmail-post-get-new-mail-hook
+ (lambda () (set-default-file-modes #o775)))
+@end lisp
+
+@item nnmail-use-long-file-names
+@vindex nnmail-use-long-file-names
+If non-@code{nil}, the mail back ends will use long file and directory
+names. Groups like @samp{mail.misc} will end up in directories
+(assuming use of @code{nnml} back end) or files (assuming use of
+@code{nnfolder} back end) like @file{mail.misc}. If it is @code{nil},
+the same group will end up in @file{mail/misc}.
+
+@item nnmail-delete-file-function
+@vindex nnmail-delete-file-function
+@findex delete-file
+Function called to delete files. It is @code{delete-file} by default.
+
+@item nnmail-cache-accepted-message-ids
+@vindex nnmail-cache-accepted-message-ids
+If non-@code{nil}, put the @code{Message-ID}s of articles imported into
+the back end (via @code{Gcc}, for instance) into the mail duplication
+discovery cache. The default is @code{nil}.
+
+@item nnmail-cache-ignore-groups
+@vindex nnmail-cache-ignore-groups
+This can be a regular expression or a list of regular expressions.
+Group names that match any of the regular expressions will never be
+recorded in the @code{Message-ID} cache.
+
+This can be useful, for example, when using Fancy Splitting
+(@pxref{Fancy Mail Splitting}) together with the function
+@code{nnmail-split-fancy-with-parent}.
+
+@end table
+
+
+@node Fancy Mail Splitting
+@subsection Fancy Mail Splitting
+@cindex mail splitting
+@cindex fancy mail splitting
+
+@vindex nnmail-split-fancy
+@findex nnmail-split-fancy
+If the rather simple, standard method for specifying how to split mail
+doesn't allow you to do what you want, you can set
+@code{nnmail-split-methods} to @code{nnmail-split-fancy}. Then you can
+play with the @code{nnmail-split-fancy} variable.
+
+Let's look at an example value of this variable first:
+
+@lisp
+;; @r{Messages from the mailer daemon are not crossposted to any of}
+;; @r{the ordinary groups. Warnings are put in a separate group}
+;; @r{from real errors.}
+(| ("from" mail (| ("subject" "warn.*" "mail.warning")
+ "mail.misc"))
+ ;; @r{Non-error messages are crossposted to all relevant}
+ ;; @r{groups, but we don't crosspost between the group for the}
+ ;; @r{(ding) list and the group for other (ding) related mail.}
+ (& (| (any "ding@@ifi\\.uio\\.no" "ding.list")
+ ("subject" "ding" "ding.misc"))
+ ;; @r{Other mailing lists@dots{}}
+ (any "procmail@@informatik\\.rwth-aachen\\.de" "procmail.list")
+ (any "SmartList@@informatik\\.rwth-aachen\\.de" "SmartList.list")
+ ;; @r{Both lists below have the same suffix, so prevent}
+ ;; @r{cross-posting to mkpkg.list of messages posted only to}
+ ;; @r{the bugs- list, but allow cross-posting when the}
+ ;; @r{message was really cross-posted.}
+ (any "bugs-mypackage@@somewhere" "mypkg.bugs")
+ (any "mypackage@@somewhere" - "bugs-mypackage" "mypkg.list")
+ ;; @r{People@dots{}}
+ (any "larsi@@ifi\\.uio\\.no" "people.Lars_Magne_Ingebrigtsen"))
+ ;; @r{Unmatched mail goes to the catch all group.}
+ "misc.misc")
+@end lisp
+
+This variable has the format of a @dfn{split}. A split is a
+(possibly) recursive structure where each split may contain other
+splits. Here are the possible split syntaxes:
+
+@table @code
+
+@item group
+If the split is a string, that will be taken as a group name. Normal
+regexp match expansion will be done. See below for examples.
+
+@c Don't fold this line.
+@item (@var{field} @var{value} [- @var{restrict} [@dots{}] ] @var{split} [@var{invert-partial}])
+The split can be a list containing at least three elements. If the
+first element @var{field} (a regexp matching a header) contains
+@var{value} (also a regexp) then store the message as specified by
+@var{split}.
+
+If @var{restrict} (yet another regexp) matches some string after
+@var{field} and before the end of the matched @var{value}, the
+@var{split} is ignored. If none of the @var{restrict} clauses match,
+@var{split} is processed.
+
+The last element @var{invert-partial} is optional. If it is
+non-@code{nil}, the match-partial-words behavior controlled by the
+variable @code{nnmail-split-fancy-match-partial-words} (see below) is
+be inverted. (New in Gnus 5.10.7)
+
+@item (| @var{split} @dots{})
+If the split is a list, and the first element is @code{|} (vertical
+bar), then process each @var{split} until one of them matches. A
+@var{split} is said to match if it will cause the mail message to be
+stored in one or more groups.
+
+@item (& @var{split} @dots{})
+If the split is a list, and the first element is @code{&}, then
+process all @var{split}s in the list.
+
+@item junk
+If the split is the symbol @code{junk}, then don't save (i.e., delete)
+this message. Use with extreme caution.
+
+@item (: @var{function} @var{arg1} @var{arg2} @dots{})
+If the split is a list, and the first element is @samp{:}, then the
+second element will be called as a function with @var{args} given as
+arguments. The function should return a @var{split}.
+
+@cindex body split
+For instance, the following function could be used to split based on the
+body of the messages:
+
+@lisp
+(defun split-on-body ()
+ (save-excursion
+ (save-restriction
+ (widen)
+ (goto-char (point-min))
+ (when (re-search-forward "Some.*string" nil t)
+ "string.group"))))
+@end lisp
+
+The buffer is narrowed to the header of the message in question when
+@var{function} is run. That's why @code{(widen)} needs to be called
+after @code{save-excursion} and @code{save-restriction} in the example
+above. Also note that with the nnimap backend, message bodies will
+not be downloaded by default. You need to set
+@code{nnimap-split-download-body} to @code{t} to do that
+(@pxref{Client-Side IMAP Splitting}).
+
+@item (! @var{func} @var{split})
+If the split is a list, and the first element is @code{!}, then
+@var{split} will be processed, and @var{func} will be called as a
+function with the result of @var{split} as argument. @var{func}
+should return a split.
+
+@item nil
+If the split is @code{nil}, it is ignored.
+
+@end table
+
+In these splits, @var{field} must match a complete field name.
+
+Normally, @var{value} in these splits must match a complete @emph{word}
+according to the fundamental mode syntax table. In other words, all
+@var{value}'s will be implicitly surrounded by @code{\<...\>} markers,
+which are word delimiters. Therefore, if you use the following split,
+for example,
+
+@example
+(any "joe" "joemail")
+@end example
+
+@noindent
+messages sent from @samp{joedavis@@foo.org} will normally not be filed
+in @samp{joemail}. If you want to alter this behavior, you can use any
+of the following three ways:
+
+@enumerate
+@item
+@vindex nnmail-split-fancy-match-partial-words
+You can set the @code{nnmail-split-fancy-match-partial-words} variable
+to non-@code{nil} in order to ignore word boundaries and instead the
+match becomes more like a grep. This variable controls whether partial
+words are matched during fancy splitting. The default value is
+@code{nil}.
+
+Note that it influences all @var{value}'s in your split rules.
+
+@item
+@var{value} beginning with @code{.*} ignores word boundaries in front of
+a word. Similarly, if @var{value} ends with @code{.*}, word boundaries
+in the rear of a word will be ignored. For example, the @var{value}
+@code{"@@example\\.com"} does not match @samp{foo@@example.com} but
+@code{".*@@example\\.com"} does.
+
+@item
+You can set the @var{invert-partial} flag in your split rules of the
+@samp{(@var{field} @var{value} @dots{})} types, aforementioned in this
+section. If the flag is set, word boundaries on both sides of a word
+are ignored even if @code{nnmail-split-fancy-match-partial-words} is
+@code{nil}. Contrarily, if the flag is set, word boundaries are not
+ignored even if @code{nnmail-split-fancy-match-partial-words} is
+non-@code{nil}. (New in Gnus 5.10.7)
+@end enumerate
+
+@vindex nnmail-split-abbrev-alist
+@var{field} and @var{value} can also be Lisp symbols, in that case
+they are expanded as specified by the variable
+@code{nnmail-split-abbrev-alist}. This is an alist of cons cells,
+where the @sc{car} of a cell contains the key, and the @sc{cdr}
+contains the associated value. Predefined entries in
+@code{nnmail-split-abbrev-alist} include:
+
+@table @code
+@item from
+Matches the @samp{From}, @samp{Sender} and @samp{Resent-From} fields.
+@item to
+Matches the @samp{To}, @samp{Cc}, @samp{Apparently-To},
+@samp{Resent-To} and @samp{Resent-Cc} fields.
+@item any
+Is the union of the @code{from} and @code{to} entries.
+@end table
+
+@vindex nnmail-split-fancy-syntax-table
+@code{nnmail-split-fancy-syntax-table} is the syntax table in effect
+when all this splitting is performed.
+
+If you want to have Gnus create groups dynamically based on some
+information in the headers (i.e., do @code{replace-match}-like
+substitutions in the group names), you can say things like:
+
+@example
+(any "debian-\\b\\(\\w+\\)@@lists.debian.org" "mail.debian.\\1")
+@end example
+
+In this example, messages sent to @samp{debian-foo@@lists.debian.org}
+will be filed in @samp{mail.debian.foo}.
+
+If the string contains the element @samp{\\&}, then the previously
+matched string will be substituted. Similarly, the elements @samp{\\1}
+up to @samp{\\9} will be substituted with the text matched by the
+groupings 1 through 9.
+
+@vindex nnmail-split-lowercase-expanded
+Where @code{nnmail-split-lowercase-expanded} controls whether the
+lowercase of the matched string should be used for the substitution.
+Setting it as non-@code{nil} is useful to avoid the creation of multiple
+groups when users send to an address using different case
+(i.e., mailing-list@@domain vs Mailing-List@@Domain). The default value
+is @code{t}.
+
+@findex nnmail-split-fancy-with-parent
+@code{nnmail-split-fancy-with-parent} is a function which allows you to
+split followups into the same groups their parents are in. Sometimes
+you can't make splitting rules for all your mail. For example, your
+boss might send you personal mail regarding different projects you are
+working on, and as you can't tell your boss to put a distinguishing
+string into the subject line, you have to resort to manually moving the
+messages into the right group. With this function, you only have to do
+it once per thread.
+
+To use this feature, you have to set @code{nnmail-treat-duplicates}
+and @code{nnmail-cache-accepted-message-ids} to a non-@code{nil}
+value. And then you can include @code{nnmail-split-fancy-with-parent}
+using the colon feature, like so:
+@lisp
+(setq nnmail-treat-duplicates 'warn ; @r{or @code{delete}}
+ nnmail-cache-accepted-message-ids t
+ nnmail-split-fancy
+ '(| (: nnmail-split-fancy-with-parent)
+ ;; @r{other splits go here}
+ ))
+@end lisp
+
+This feature works as follows: when @code{nnmail-treat-duplicates} is
+non-@code{nil}, Gnus records the message id of every message it sees
+in the file specified by the variable
+@code{nnmail-message-id-cache-file}, together with the group it is in
+(the group is omitted for non-mail messages). When mail splitting is
+invoked, the function @code{nnmail-split-fancy-with-parent} then looks
+at the References (and In-Reply-To) header of each message to split
+and searches the file specified by @code{nnmail-message-id-cache-file}
+for the message ids. When it has found a parent, it returns the
+corresponding group name unless the group name matches the regexp
+@code{nnmail-split-fancy-with-parent-ignore-groups}. It is
+recommended that you set @code{nnmail-message-id-cache-length} to a
+somewhat higher number than the default so that the message ids are
+still in the cache. (A value of 5000 appears to create a file some
+300 kBytes in size.)
+@vindex nnmail-cache-accepted-message-ids
+When @code{nnmail-cache-accepted-message-ids} is non-@code{nil}, Gnus
+also records the message ids of moved articles, so that the followup
+messages goes into the new group.
+
+Also see the variable @code{nnmail-cache-ignore-groups} if you don't
+want certain groups to be recorded in the cache. For example, if all
+outgoing messages are written to an ``outgoing'' group, you could set
+@code{nnmail-cache-ignore-groups} to match that group name.
+Otherwise, answers to all your messages would end up in the
+``outgoing'' group.
+
+
+@node Group Mail Splitting
+@subsection Group Mail Splitting
+@cindex mail splitting
+@cindex group mail splitting
+
+@findex gnus-group-split
+If you subscribe to dozens of mailing lists but you don't want to
+maintain mail splitting rules manually, group mail splitting is for you.
+You just have to set @code{to-list} and/or @code{to-address} in group
+parameters or group customization and set @code{nnmail-split-methods} to
+@code{gnus-group-split}. This splitting function will scan all groups
+for those parameters and split mail accordingly, i.e., messages posted
+from or to the addresses specified in the parameters @code{to-list} or
+@code{to-address} of a mail group will be stored in that group.
+
+Sometimes, mailing lists have multiple addresses, and you may want mail
+splitting to recognize them all: just set the @code{extra-aliases} group
+parameter to the list of additional addresses and it's done. If you'd
+rather use a regular expression, set @code{split-regexp}.
+
+All these parameters in a group will be used to create an
+@code{nnmail-split-fancy} split, in which the @var{field} is @samp{any},
+the @var{value} is a single regular expression that matches
+@code{to-list}, @code{to-address}, all of @code{extra-aliases} and all
+matches of @code{split-regexp}, and the @var{split} is the name of the
+group. @var{restrict}s are also supported: just set the
+@code{split-exclude} parameter to a list of regular expressions.
+
+If you can't get the right split to be generated using all these
+parameters, or you just need something fancier, you can set the
+parameter @code{split-spec} to an @code{nnmail-split-fancy} split. In
+this case, all other aforementioned parameters will be ignored by
+@code{gnus-group-split}. In particular, @code{split-spec} may be set to
+@code{nil}, in which case the group will be ignored by
+@code{gnus-group-split}.
+
+@vindex gnus-group-split-default-catch-all-group
+@code{gnus-group-split} will do cross-posting on all groups that match,
+by defining a single @code{&} fancy split containing one split for each
+group. If a message doesn't match any split, it will be stored in the
+group named in @code{gnus-group-split-default-catch-all-group}, unless
+some group has @code{split-spec} set to @code{catch-all}, in which case
+that group is used as the catch-all group. Even though this variable is
+often used just to name a group, it may also be set to an arbitrarily
+complex fancy split (after all, a group name is a fancy split), and this
+may be useful to split mail that doesn't go to any mailing list to
+personal mail folders. Note that this fancy split is added as the last
+element of a @code{|} split list that also contains a @code{&} split
+with the rules extracted from group parameters.
+
+It's time for an example. Assume the following group parameters have
+been defined:
+
+@example
+nnml:mail.bar:
+((to-address . "bar@@femail.com")
+ (split-regexp . ".*@@femail\\.com"))
+nnml:mail.foo:
+((to-list . "foo@@nowhere.gov")
+ (extra-aliases "foo@@localhost" "foo-redist@@home")
+ (split-exclude "bugs-foo" "rambling-foo")
+ (admin-address . "foo-request@@nowhere.gov"))
+nnml:mail.others:
+((split-spec . catch-all))
+@end example
+
+Setting @code{nnmail-split-methods} to @code{gnus-group-split} will
+behave as if @code{nnmail-split-fancy} had been selected and variable
+@code{nnmail-split-fancy} had been set as follows:
+
+@lisp
+(| (& (any "\\(bar@@femail\\.com\\|.*@@femail\\.com\\)" "mail.bar")
+ (any "\\(foo@@nowhere\\.gov\\|foo@@localhost\\|foo-redist@@home\\)"
+ - "bugs-foo" - "rambling-foo" "mail.foo"))
+ "mail.others")
+@end lisp
+
+@findex gnus-group-split-fancy
+If you'd rather not use group splitting for all your mail groups, you
+may use it for only some of them, by using @code{nnmail-split-fancy}
+splits like this:
+
+@lisp
+(: gnus-group-split-fancy @var{groups} @var{no-crosspost} @var{catch-all})
+@end lisp
+
+@var{groups} may be a regular expression or a list of group names whose
+parameters will be scanned to generate the output split.
+@var{no-crosspost} can be used to disable cross-posting; in this case, a
+single @code{|} split will be output. @var{catch-all} is the fall back
+fancy split, used like @code{gnus-group-split-default-catch-all-group}.
+If @var{catch-all} is @code{nil}, or if @code{split-regexp} matches the
+empty string in any selected group, no catch-all split will be issued.
+Otherwise, if some group has @code{split-spec} set to @code{catch-all},
+this group will override the value of the @var{catch-all} argument.
+
+@findex gnus-group-split-setup
+Unfortunately, scanning all groups and their parameters can be quite
+slow, especially considering that it has to be done for every message.
+But don't despair! The function @code{gnus-group-split-setup} can be
+used to enable @code{gnus-group-split} in a much more efficient way. It
+sets @code{nnmail-split-methods} to @code{nnmail-split-fancy} and sets
+@code{nnmail-split-fancy} to the split produced by
+@code{gnus-group-split-fancy}. Thus, the group parameters are only
+scanned once, no matter how many messages are split.
+
+@findex gnus-group-split-update
+However, if you change group parameters, you'd have to update
+@code{nnmail-split-fancy} manually. You can do it by running
+@code{gnus-group-split-update}. If you'd rather have it updated
+automatically, just tell @code{gnus-group-split-setup} to do it for
+you. For example, add to your @file{~/.gnus.el}:
+
+@lisp
+(gnus-group-split-setup @var{auto-update} @var{catch-all})
+@end lisp
+
+If @var{auto-update} is non-@code{nil}, @code{gnus-group-split-update}
+will be added to @code{nnmail-pre-get-new-mail-hook}, so you won't ever
+have to worry about updating @code{nnmail-split-fancy} again. If you
+don't omit @var{catch-all} (it's optional, equivalent to @code{nil}),
+@code{gnus-group-split-default-catch-all-group} will be set to its
+value.
+
+@vindex gnus-group-split-updated-hook
+Because you may want to change @code{nnmail-split-fancy} after it is set
+by @code{gnus-group-split-update}, this function will run
+@code{gnus-group-split-updated-hook} just before finishing.
+
+@node Incorporating Old Mail
+@subsection Incorporating Old Mail
+@cindex incorporating old mail
+@cindex import old mail
+
+Most people have lots of old mail stored in various file formats. If
+you have set up Gnus to read mail using one of the spiffy Gnus mail
+back ends, you'll probably wish to have that old mail incorporated into
+your mail groups.
+
+Doing so can be quite easy.
+
+To take an example: You're reading mail using @code{nnml}
+(@pxref{Mail Spool}), and have set @code{nnmail-split-methods} to a
+satisfactory value (@pxref{Splitting Mail}). You have an old Unix mbox
+file filled with important, but old, mail. You want to move it into
+your @code{nnml} groups.
+
+Here's how:
+
+@enumerate
+@item
+Go to the group buffer.
+
+@item
+Type @kbd{G f} and give the file name to the mbox file when prompted to create an
+@code{nndoc} group from the mbox file (@pxref{Foreign Groups}).
+
+@item
+Type @kbd{SPACE} to enter the newly created group.
+
+@item
+Type @kbd{M P b} to process-mark all articles in this group's buffer
+(@pxref{Setting Process Marks}).
+
+@item
+Type @kbd{B r} to respool all the process-marked articles, and answer
+@samp{nnml} when prompted (@pxref{Mail Group Commands}).
+@end enumerate
+
+All the mail messages in the mbox file will now also be spread out over
+all your @code{nnml} groups. Try entering them and check whether things
+have gone without a glitch. If things look ok, you may consider
+deleting the mbox file, but I wouldn't do that unless I was absolutely
+sure that all the mail has ended up where it should be.
+
+Respooling is also a handy thing to do if you're switching from one mail
+back end to another. Just respool all the mail in the old mail groups
+using the new mail back end.
+
+
+@node Expiring Mail
+@subsection Expiring Mail
+@cindex article expiry
+@cindex expiring mail
+
+Traditional mail readers have a tendency to remove mail articles when
+you mark them as read, in some way. Gnus takes a fundamentally
+different approach to mail reading.
+
+Gnus basically considers mail just to be news that has been received in
+a rather peculiar manner. It does not think that it has the power to
+actually change the mail, or delete any mail messages. If you enter a
+mail group, and mark articles as ``read'', or kill them in some other
+fashion, the mail articles will still exist on the system. I repeat:
+Gnus will not delete your old, read mail. Unless you ask it to, of
+course.
+
+To make Gnus get rid of your unwanted mail, you have to mark the
+articles as @dfn{expirable}. (With the default key bindings, this means
+that you have to type @kbd{E}.) This does not mean that the articles
+will disappear right away, however. In general, a mail article will be
+deleted from your system if, 1) it is marked as expirable, AND 2) it is
+more than one week old. If you do not mark an article as expirable, it
+will remain on your system until hell freezes over. This bears
+repeating one more time, with some spurious capitalizations: IF you do
+NOT mark articles as EXPIRABLE, Gnus will NEVER delete those ARTICLES.
+
+@vindex gnus-auto-expirable-marks
+You do not have to mark articles as expirable by hand. Gnus provides
+two features, called ``auto-expire'' and ``total-expire'', that can help you
+with this. In a nutshell, ``auto-expire'' means that Gnus hits @kbd{E}
+for you when you select an article. And ``total-expire'' means that Gnus
+considers all articles as expirable that are read. So, in addition to
+the articles marked @samp{E}, also the articles marked @samp{r},
+@samp{R}, @samp{O}, @samp{K}, @samp{Y} (and so on) are considered
+expirable. @code{gnus-auto-expirable-marks} has the full list of
+these marks.
+
+When should either auto-expire or total-expire be used? Most people
+who are subscribed to mailing lists split each list into its own group
+and then turn on auto-expire or total-expire for those groups.
+(@xref{Splitting Mail}, for more information on splitting each list
+into its own group.)
+
+Which one is better, auto-expire or total-expire? It's not easy to
+answer. Generally speaking, auto-expire is probably faster. Another
+advantage of auto-expire is that you get more marks to work with: for
+the articles that are supposed to stick around, you can still choose
+between tick and dormant and read marks. But with total-expire, you
+only have dormant and ticked to choose from. The advantage of
+total-expire is that it works well with adaptive scoring (@pxref{Adaptive
+Scoring}). Auto-expire works with normal scoring but not with adaptive
+scoring.
+
+@vindex gnus-auto-expirable-newsgroups
+Groups that match the regular expression
+@code{gnus-auto-expirable-newsgroups} will have all articles that you
+read marked as expirable automatically. All articles marked as
+expirable have an @samp{E} in the first column in the summary buffer.
+
+By default, if you have auto expiry switched on, Gnus will mark all the
+articles you read as expirable, no matter if they were read or unread
+before. To avoid having articles marked as read marked as expirable
+automatically, you can put something like the following in your
+@file{~/.gnus.el} file:
+
+@vindex gnus-mark-article-hook
+@lisp
+(remove-hook 'gnus-mark-article-hook
+ 'gnus-summary-mark-read-and-unread-as-read)
+(add-hook 'gnus-mark-article-hook 'gnus-summary-mark-unread-as-read)
+@end lisp
+
+Note that making a group auto-expirable doesn't mean that all read
+articles are expired---only the articles marked as expirable
+will be expired. Also note that using the @kbd{d} command won't make
+articles expirable---only semi-automatic marking of articles as read will
+mark the articles as expirable in auto-expirable groups.
+
+Let's say you subscribe to a couple of mailing lists, and you want the
+articles you have read to disappear after a while:
+
+@lisp
+(setq gnus-auto-expirable-newsgroups
+ "mail.nonsense-list\\|mail.nice-list")
+@end lisp
+
+Another way to have auto-expiry happen is to have the element
+@code{auto-expire} in the group parameters of the group.
+
+If you use adaptive scoring (@pxref{Adaptive Scoring}) and
+auto-expiring, you'll have problems. Auto-expiring and adaptive scoring
+don't really mix very well.
+
+@vindex nnmail-expiry-wait
+The @code{nnmail-expiry-wait} variable supplies the default time an
+expirable article has to live. Gnus starts counting days from when the
+message @emph{arrived}, not from when it was sent. The default is seven
+days.
+
+Gnus also supplies a function that lets you fine-tune how long articles
+are to live, based on what group they are in. Let's say you want to
+have one month expiry period in the @samp{mail.private} group, a one day
+expiry period in the @samp{mail.junk} group, and a six day expiry period
+everywhere else:
+
+@vindex nnmail-expiry-wait-function
+@lisp
+(setq nnmail-expiry-wait-function
+ (lambda (group)
+ (cond ((string= group "mail.private")
+ 31)
+ ((string= group "mail.junk")
+ 1)
+ ((string= group "important")
+ 'never)
+ (t
+ 6))))
+@end lisp
+
+The group names this function is fed are ``unadorned'' group
+names---no @samp{nnml:} prefixes and the like.
+
+The @code{nnmail-expiry-wait} variable and
+@code{nnmail-expiry-wait-function} function can either be a number (not
+necessarily an integer) or one of the symbols @code{immediate} or
+@code{never}.
+
+You can also use the @code{expiry-wait} group parameter to selectively
+change the expiry period (@pxref{Group Parameters}).
+
+@vindex nnmail-expiry-target
+The normal action taken when expiring articles is to delete them.
+However, in some circumstances it might make more sense to move them
+to other groups instead of deleting them. The variable
+@code{nnmail-expiry-target} (and the @code{expiry-target} group
+parameter) controls this. The variable supplies a default value for
+all groups, which can be overridden for specific groups by the group
+parameter. default value is @code{delete}, but this can also be a
+string (which should be the name of the group the message should be
+moved to), or a function (which will be called in a buffer narrowed to
+the message in question, and with the name of the group being moved
+from as its parameter) which should return a target---either a group
+name or @code{delete}.
+
+Here's an example for specifying a group name:
+@lisp
+(setq nnmail-expiry-target "nnml:expired")
+@end lisp
+
+@findex nnmail-fancy-expiry-target
+@vindex nnmail-fancy-expiry-targets
+Gnus provides a function @code{nnmail-fancy-expiry-target} which will
+expire mail to groups according to the variable
+@code{nnmail-fancy-expiry-targets}. Here's an example:
+
+@lisp
+ (setq nnmail-expiry-target 'nnmail-fancy-expiry-target
+ nnmail-fancy-expiry-targets
+ '((to-from "boss" "nnfolder:Work")
+ ("subject" "IMPORTANT" "nnfolder:IMPORTANT.%Y.%b")
+ ("from" ".*" "nnfolder:Archive-%Y")))
+@end lisp
+
+With this setup, any mail that has @code{IMPORTANT} in its Subject
+header and was sent in the year @code{YYYY} and month @code{MMM}, will
+get expired to the group @code{nnfolder:IMPORTANT.YYYY.MMM}. If its
+From or To header contains the string @code{boss}, it will get expired
+to @code{nnfolder:Work}. All other mail will get expired to
+@code{nnfolder:Archive-YYYY}.
+
+@vindex nnmail-keep-last-article
+If @code{nnmail-keep-last-article} is non-@code{nil}, Gnus will never
+expire the final article in a mail newsgroup. This is to make life
+easier for procmail users.
+
+@vindex gnus-total-expirable-newsgroups
+By the way: That line up there, about Gnus never expiring non-expirable
+articles, is a lie. If you put @code{total-expire} in the group
+parameters, articles will not be marked as expirable, but all read
+articles will be put through the expiry process. Use with extreme
+caution. Even more dangerous is the
+@code{gnus-total-expirable-newsgroups} variable. All groups that match
+this regexp will have all read articles put through the expiry process,
+which means that @emph{all} old mail articles in the groups in question
+will be deleted after a while. Use with extreme caution, and don't come
+crying to me when you discover that the regexp you used matched the
+wrong group and all your important mail has disappeared. Be a
+@emph{man}! Or a @emph{woman}! Whatever you feel more comfortable
+with! So there!
+
+Most people make most of their mail groups total-expirable, though.
+
+@vindex gnus-inhibit-user-auto-expire
+If @code{gnus-inhibit-user-auto-expire} is non-@code{nil}, user marking
+commands will not mark an article as expirable, even if the group has
+auto-expire turned on.
+
+@vindex gnus-mark-copied-or-moved-articles-as-expirable
+The expirable marks of articles will be removed when copying or moving
+them to a group in which auto-expire is not turned on. This is for
+preventing articles from being expired unintentionally. On the other
+hand, to a group that has turned auto-expire on, the expirable marks of
+articles that are copied or moved will not be changed by default. I.e.,
+when copying or moving to such a group, articles that were expirable
+will be left expirable and ones that were not expirable will not be
+marked as expirable. So, even though in auto-expire groups, some
+articles will never get expired (unless you read them again). If you
+don't side with that behavior that unexpirable articles may be mixed
+into auto-expire groups, you can set
+@code{gnus-mark-copied-or-moved-articles-as-expirable} to a
+non-@code{nil} value. In that case, articles that have been read will
+be marked as expirable automatically when being copied or moved to a
+group that has auto-expire turned on. The default value is @code{nil}.
+
+
+@node Washing Mail
+@subsection Washing Mail
+@cindex mail washing
+@cindex list server brain damage
+@cindex incoming mail treatment
+
+Mailers and list servers are notorious for doing all sorts of really,
+really stupid things with mail. ``Hey, RFC 822 doesn't explicitly
+prohibit us from adding the string @code{wE aRe ElItE!!!!!1!!} to the
+end of all lines passing through our server, so let's do that!!!!1!''
+Yes, but RFC 822 wasn't designed to be read by morons. Things that were
+considered to be self-evident were not discussed. So. Here we are.
+
+Case in point: The German version of Microsoft Exchange adds @samp{AW:
+} to the subjects of replies instead of @samp{Re: }. I could pretend to
+be shocked and dismayed by this, but I haven't got the energy. It is to
+laugh.
+
+Gnus provides a plethora of functions for washing articles while
+displaying them, but it might be nicer to do the filtering before
+storing the mail to disk. For that purpose, we have three hooks and
+various functions that can be put in these hooks.
+
+@table @code
+@item nnmail-prepare-incoming-hook
+@vindex nnmail-prepare-incoming-hook
+This hook is called before doing anything with the mail and is meant for
+grand, sweeping gestures. It is called in a buffer that contains all
+the new, incoming mail. Functions to be used include:
+
+@table @code
+@item nnheader-ms-strip-cr
+@findex nnheader-ms-strip-cr
+Remove trailing carriage returns from each line. This is default on
+Emacs running on MS machines.
+
+@end table
+
+@item nnmail-prepare-incoming-header-hook
+@vindex nnmail-prepare-incoming-header-hook
+This hook is called narrowed to each header. It can be used when
+cleaning up the headers. Functions that can be used include:
+
+@table @code
+@item nnmail-remove-leading-whitespace
+@findex nnmail-remove-leading-whitespace
+Clear leading white space that ``helpful'' listservs have added to the
+headers to make them look nice. Aaah.
+
+(Note that this function works on both the header on the body of all
+messages, so it is a potentially dangerous function to use (if a body
+of a message contains something that looks like a header line). So
+rather than fix the bug, it is of course the right solution to make it
+into a feature by documenting it.)
+
+@item nnmail-remove-list-identifiers
+@findex nnmail-remove-list-identifiers
+Some list servers add an identifier---for example, @samp{(idm)}---to the
+beginning of all @code{Subject} headers. I'm sure that's nice for
+people who use stone age mail readers. This function will remove
+strings that match the @code{nnmail-list-identifiers} regexp, which can
+also be a list of regexp. @code{nnmail-list-identifiers} may not contain
+@code{\\(..\\)}.
+
+For instance, if you want to remove the @samp{(idm)} and the
+@samp{nagnagnag} identifiers:
+
+@lisp
+(setq nnmail-list-identifiers
+ '("(idm)" "nagnagnag"))
+@end lisp
+
+This can also be done non-destructively with
+@code{gnus-list-identifiers}, @xref{Article Hiding}.
+
+@item nnmail-remove-tabs
+@findex nnmail-remove-tabs
+Translate all @samp{TAB} characters into @samp{SPACE} characters.
+
+@item nnmail-ignore-broken-references
+@findex nnmail-ignore-broken-references
+@c @findex nnmail-fix-eudora-headers
+@cindex Eudora
+@cindex Pegasus
+Some mail user agents (e.g., Eudora and Pegasus) produce broken
+@code{References} headers, but correct @code{In-Reply-To} headers. This
+function will get rid of the @code{References} header if the headers
+contain a line matching the regular expression
+@code{nnmail-broken-references-mailers}.
+
+@end table
+
+@item nnmail-prepare-incoming-message-hook
+@vindex nnmail-prepare-incoming-message-hook
+This hook is called narrowed to each message. Functions to be used
+include:
+
+@table @code
+@item article-de-quoted-unreadable
+@findex article-de-quoted-unreadable
+Decode Quoted Readable encoding.
+
+@end table
+@end table
+
+
+@node Duplicates
+@subsection Duplicates
+
+@vindex nnmail-treat-duplicates
+@vindex nnmail-message-id-cache-length
+@vindex nnmail-message-id-cache-file
+@cindex duplicate mails
+If you are a member of a couple of mailing lists, you will sometimes
+receive two copies of the same mail. This can be quite annoying, so
+@code{nnmail} checks for and treats any duplicates it might find. To do
+this, it keeps a cache of old @code{Message-ID}s:
+@code{nnmail-message-id-cache-file}, which is @file{~/.nnmail-cache} by
+default. The approximate maximum number of @code{Message-ID}s stored
+there is controlled by the @code{nnmail-message-id-cache-length}
+variable, which is 1000 by default. (So 1000 @code{Message-ID}s will be
+stored.) If all this sounds scary to you, you can set
+@code{nnmail-treat-duplicates} to @code{warn} (which is what it is by
+default), and @code{nnmail} won't delete duplicate mails. Instead it
+will insert a warning into the head of the mail saying that it thinks
+that this is a duplicate of a different message.
+
+This variable can also be a function. If that's the case, the function
+will be called from a buffer narrowed to the message in question with
+the @code{Message-ID} as a parameter. The function must return either
+@code{nil}, @code{warn}, or @code{delete}.
+
+You can turn this feature off completely by setting the variable to
+@code{nil}.
+
+If you want all the duplicate mails to be put into a special
+@dfn{duplicates} group, you could do that using the normal mail split
+methods:
+
+@lisp
+(setq nnmail-split-fancy
+ '(| ;; @r{Messages duplicates go to a separate group.}
+ ("gnus-warning" "duplicat\\(e\\|ion\\) of message" "duplicate")
+ ;; @r{Message from daemons, postmaster, and the like to another.}
+ (any mail "mail.misc")
+ ;; @r{Other rules.}
+ [...] ))
+@end lisp
+@noindent
+Or something like:
+@lisp
+(setq nnmail-split-methods
+ '(("duplicates" "^Gnus-Warning:.*duplicate")
+ ;; @r{Other rules.}
+ [...]))
+@end lisp
+
+Here's a neat feature: If you know that the recipient reads her mail
+with Gnus, and that she has @code{nnmail-treat-duplicates} set to
+@code{delete}, you can send her as many insults as you like, just by
+using a @code{Message-ID} of a mail that you know that she's already
+received. Think of all the fun! She'll never see any of it! Whee!
+
+
+@node Not Reading Mail
+@subsection Not Reading Mail
+
+If you start using any of the mail back ends, they have the annoying
+habit of assuming that you want to read mail with them. This might not
+be unreasonable, but it might not be what you want.
+
+If you set @code{mail-sources} and @code{nnmail-spool-file} to
+@code{nil}, none of the back ends will ever attempt to read incoming
+mail, which should help.
+
+@vindex nnbabyl-get-new-mail
+@vindex nnmbox-get-new-mail
+@vindex nnml-get-new-mail
+@vindex nnmh-get-new-mail
+@vindex nnfolder-get-new-mail
+This might be too much, if, for instance, you are reading mail quite
+happily with @code{nnml} and just want to peek at some old (pre-Emacs
+23) Rmail file you have stashed away with @code{nnbabyl}. All back ends have
+variables called back-end-@code{get-new-mail}. If you want to disable
+the @code{nnbabyl} mail reading, you edit the virtual server for the
+group to have a setting where @code{nnbabyl-get-new-mail} to @code{nil}.
+
+All the mail back ends will call @code{nn}*@code{-prepare-save-mail-hook}
+narrowed to the article to be saved before saving it when reading
+incoming mail.
+
+
+@node Choosing a Mail Back End
+@subsection Choosing a Mail Back End
+
+Gnus will read the mail spool when you activate a mail group. The mail
+file is first copied to your home directory. What happens after that
+depends on what format you want to store your mail in.
+
+There are six different mail back ends in the standard Gnus, and more
+back ends are available separately. The mail back end most people use
+(because it is possibly the fastest) is @code{nnml} (@pxref{Mail
+Spool}).
+
+@menu
+* Unix Mail Box:: Using the (quite) standard Un*x mbox.
+* Babyl:: Babyl was used by older versions of Rmail.
+* Mail Spool:: Store your mail in a private spool?
+* MH Spool:: An mhspool-like back end.
+* Maildir:: Another one-file-per-message format.
+* nnmaildir Group Parameters::
+* Article Identification::
+* NOV Data::
+* Article Marks::
+* Mail Folders:: Having one file for each group.
+* Comparing Mail Back Ends:: An in-depth looks at pros and cons.
+@end menu
+
+
+
+@node Unix Mail Box
+@subsubsection Unix Mail Box
+@cindex nnmbox
+@cindex unix mail box
+
+@vindex nnmbox-active-file
+@vindex nnmbox-mbox-file
+The @dfn{nnmbox} back end will use the standard Un*x mbox file to store
+mail. @code{nnmbox} will add extra headers to each mail article to say
+which group it belongs in.
+
+Virtual server settings:
+
+@table @code
+@item nnmbox-mbox-file
+@vindex nnmbox-mbox-file
+The name of the mail box in the user's home directory. Default is
+@file{~/mbox}.
+
+@item nnmbox-active-file
+@vindex nnmbox-active-file
+The name of the active file for the mail box. Default is
+@file{~/.mbox-active}.
+
+@item nnmbox-get-new-mail
+@vindex nnmbox-get-new-mail
+If non-@code{nil}, @code{nnmbox} will read incoming mail and split it
+into groups. Default is @code{t}.
+@end table
+
+
+@node Babyl
+@subsubsection Babyl
+@cindex nnbabyl
+
+@vindex nnbabyl-active-file
+@vindex nnbabyl-mbox-file
+The @dfn{nnbabyl} back end will use a Babyl mail box to store mail.
+@code{nnbabyl} will add extra headers to each mail article to say which
+group it belongs in.
+
+Virtual server settings:
+
+@table @code
+@item nnbabyl-mbox-file
+@vindex nnbabyl-mbox-file
+The name of the Babyl file. The default is @file{~/RMAIL}
+
+@item nnbabyl-active-file
+@vindex nnbabyl-active-file
+The name of the active file for the Babyl file. The default is
+@file{~/.rmail-active}
+
+@item nnbabyl-get-new-mail
+@vindex nnbabyl-get-new-mail
+If non-@code{nil}, @code{nnbabyl} will read incoming mail. Default is
+@code{t}
+@end table
+
+
+@node Mail Spool
+@subsubsection Mail Spool
+@cindex nnml
+@cindex mail @acronym{NOV} spool
+
+The @dfn{nnml} spool mail format isn't compatible with any other known
+format. It should be used with some caution.
+
+@vindex nnml-directory
+If you use this back end, Gnus will split all incoming mail into files,
+one file for each mail, and put the articles into the corresponding
+directories under the directory specified by the @code{nnml-directory}
+variable. The default value is @file{~/Mail/}.
+
+You do not have to create any directories beforehand; Gnus will take
+care of all that.
+
+If you have a strict limit as to how many files you are allowed to store
+in your account, you should not use this back end. As each mail gets its
+own file, you might very well occupy thousands of inodes within a few
+weeks. If this is no problem for you, and it isn't a problem for you
+having your friendly systems administrator walking around, madly,
+shouting ``Who is eating all my inodes?! Who? Who!?!'', then you should
+know that this is probably the fastest format to use. You do not have
+to trudge through a big mbox file just to read your new mail.
+
+@code{nnml} is probably the slowest back end when it comes to article
+splitting. It has to create lots of files, and it also generates
+@acronym{NOV} databases for the incoming mails. This makes it possibly the
+fastest back end when it comes to reading mail.
+
+Virtual server settings:
+
+@table @code
+@item nnml-directory
+@vindex nnml-directory
+All @code{nnml} directories will be placed under this directory. The
+default is the value of @code{message-directory} (whose default value
+is @file{~/Mail}).
+
+@item nnml-active-file
+@vindex nnml-active-file
+The active file for the @code{nnml} server. The default is
+@file{~/Mail/active}.
+
+@item nnml-newsgroups-file
+@vindex nnml-newsgroups-file
+The @code{nnml} group descriptions file. @xref{Newsgroups File
+Format}. The default is @file{~/Mail/newsgroups}.
+
+@item nnml-get-new-mail
+@vindex nnml-get-new-mail
+If non-@code{nil}, @code{nnml} will read incoming mail. The default is
+@code{t}.
+
+@item nnml-nov-is-evil
+@vindex nnml-nov-is-evil
+If non-@code{nil}, this back end will ignore any @acronym{NOV} files. The
+default is @code{nil}.
+
+@item nnml-nov-file-name
+@vindex nnml-nov-file-name
+The name of the @acronym{NOV} files. The default is @file{.overview}.
+
+@item nnml-prepare-save-mail-hook
+@vindex nnml-prepare-save-mail-hook
+Hook run narrowed to an article before saving.
+
+@item nnml-use-compressed-files
+@vindex nnml-use-compressed-files
+If non-@code{nil}, @code{nnml} will allow using compressed message
+files. This requires @code{auto-compression-mode} to be enabled
+(@pxref{Compressed Files, ,Compressed Files, emacs, The Emacs Manual}).
+If the value of @code{nnml-use-compressed-files} is a string, it is used
+as the file extension specifying the compression program. You can set it
+to @samp{.bz2} if your Emacs supports it. A value of @code{t} is
+equivalent to @samp{.gz}.
+
+@item nnml-compressed-files-size-threshold
+@vindex nnml-compressed-files-size-threshold
+Default size threshold for compressed message files. Message files with
+bodies larger than that many characters will be automatically compressed
+if @code{nnml-use-compressed-files} is non-@code{nil}.
+
+@end table
+
+@findex nnml-generate-nov-databases
+If your @code{nnml} groups and @acronym{NOV} files get totally out of
+whack, you can do a complete update by typing @kbd{M-x
+nnml-generate-nov-databases}. This command will trawl through the
+entire @code{nnml} hierarchy, looking at each and every article, so it
+might take a while to complete. A better interface to this
+functionality can be found in the server buffer (@pxref{Server
+Commands}).
+
+
+@node MH Spool
+@subsubsection MH Spool
+@cindex nnmh
+@cindex mh-e mail spool
+
+@code{nnmh} is just like @code{nnml}, except that is doesn't generate
+@acronym{NOV} databases and it doesn't keep an active file or marks
+file. This makes @code{nnmh} a @emph{much} slower back end than
+@code{nnml}, but it also makes it easier to write procmail scripts
+for.
+
+Virtual server settings:
+
+@table @code
+@item nnmh-directory
+@vindex nnmh-directory
+All @code{nnmh} directories will be located under this directory. The
+default is the value of @code{message-directory} (whose default is
+@file{~/Mail})
+
+@item nnmh-get-new-mail
+@vindex nnmh-get-new-mail
+If non-@code{nil}, @code{nnmh} will read incoming mail. The default is
+@code{t}.
+
+@item nnmh-be-safe
+@vindex nnmh-be-safe
+If non-@code{nil}, @code{nnmh} will go to ridiculous lengths to make
+sure that the articles in the folder are actually what Gnus thinks
+they are. It will check date stamps and stat everything in sight, so
+setting this to @code{t} will mean a serious slow-down. If you never
+use anything but Gnus to read the @code{nnmh} articles, you do not
+have to set this variable to @code{t}. The default is @code{nil}.
+@end table
+
+
+@node Maildir
+@subsubsection Maildir
+@cindex nnmaildir
+@cindex maildir
+
+@code{nnmaildir} stores mail in the maildir format, with each maildir
+corresponding to a group in Gnus. This format is documented here:
+@uref{http://cr.yp.to/proto/maildir.html} and here:
+@uref{http://www.qmail.org/man/man5/maildir.html}. @code{nnmaildir}
+also stores extra information in the @file{.nnmaildir/} directory
+within a maildir.
+
+Maildir format was designed to allow concurrent deliveries and
+reading, without needing locks. With other back ends, you would have
+your mail delivered to a spool of some kind, and then you would
+configure Gnus to split mail from that spool into your groups. You
+can still do that with @code{nnmaildir}, but the more common
+configuration is to have your mail delivered directly to the maildirs
+that appear as group in Gnus.
+
+@code{nnmaildir} is designed to be perfectly reliable: @kbd{C-g} will
+never corrupt its data in memory, and @code{SIGKILL} will never
+corrupt its data in the filesystem.
+
+@code{nnmaildir} stores article marks and @acronym{NOV} data in each
+maildir. So you can copy a whole maildir from one Gnus setup to
+another, and you will keep your marks.
+
+Virtual server settings:
+
+@table @code
+@item directory
+For each of your @code{nnmaildir} servers (it's very unlikely that
+you'd need more than one), you need to create a directory and populate
+it with maildirs or symlinks to maildirs (and nothing else; do not
+choose a directory already used for other purposes). Each maildir
+will be represented in Gnus as a newsgroup on that server; the
+filename of the symlink will be the name of the group. Any filenames
+in the directory starting with @samp{.} are ignored. The directory is
+scanned when you first start Gnus, and each time you type @kbd{g} in
+the group buffer; if any maildirs have been removed or added,
+@code{nnmaildir} notices at these times.
+
+The value of the @code{directory} parameter should be a Lisp form
+which is processed by @code{eval} and @code{expand-file-name} to get
+the path of the directory for this server. The form is @code{eval}ed
+only when the server is opened; the resulting string is used until the
+server is closed. (If you don't know about forms and @code{eval},
+don't worry---a simple string will work.) This parameter is not
+optional; you must specify it. I don't recommend using
+@code{"~/Mail"} or a subdirectory of it; several other parts of Gnus
+use that directory by default for various things, and may get confused
+if @code{nnmaildir} uses it too. @code{"~/.nnmaildir"} is a typical
+value.
+
+@item target-prefix
+This should be a Lisp form which is processed by @code{eval} and
+@code{expand-file-name}. The form is @code{eval}ed only when the
+server is opened; the resulting string is used until the server is
+closed.
+
+When you create a group on an @code{nnmaildir} server, the maildir is
+created with @code{target-prefix} prepended to its name, and a symlink
+pointing to that maildir is created, named with the plain group name.
+So if @code{directory} is @code{"~/.nnmaildir"} and
+@code{target-prefix} is @code{"../maildirs/"}, then when you create
+the group @code{foo}, @code{nnmaildir} will create
+@file{~/.nnmaildir/../maildirs/foo} as a maildir, and will create
+@file{~/.nnmaildir/foo} as a symlink pointing to
+@file{../maildirs/foo}.
+
+You can set @code{target-prefix} to a string without any slashes to
+create both maildirs and symlinks in the same @code{directory}; in
+this case, any maildirs found in @code{directory} whose names start
+with @code{target-prefix} will not be listed as groups (but the
+symlinks pointing to them will be).
+
+As a special case, if @code{target-prefix} is @code{""} (the default),
+then when you create a group, the maildir will be created in
+@code{directory} without a corresponding symlink. Beware that you
+cannot use @code{gnus-group-delete-group} on such groups without the
+@code{force} argument.
+
+@item directory-files
+This should be a function with the same interface as
+@code{directory-files} (such as @code{directory-files} itself). It is
+used to scan the server's @code{directory} for maildirs. This
+parameter is optional; the default is
+@code{nnheader-directory-files-safe} if
+@code{nnheader-directory-files-is-safe} is @code{nil}, and
+@code{directory-files} otherwise.
+(@code{nnheader-directory-files-is-safe} is checked only once when the
+server is opened; if you want to check it each time the directory is
+scanned, you'll have to provide your own function that does that.)
+
+@item get-new-mail
+If non-@code{nil}, then after scanning for new mail in the group
+maildirs themselves as usual, this server will also incorporate mail
+the conventional Gnus way, from @code{mail-sources} according to
+@code{nnmail-split-methods} or @code{nnmail-split-fancy}. The default
+value is @code{nil}.
+
+Do @emph{not} use the same maildir both in @code{mail-sources} and as
+an @code{nnmaildir} group. The results might happen to be useful, but
+that would be by chance, not by design, and the results might be
+different in the future. If your split rules create new groups,
+remember to supply a @code{create-directory} server parameter.
+@end table
+
+@node nnmaildir Group Parameters
+@subsubsection Group parameters
+
+@code{nnmaildir} uses several group parameters. It's safe to ignore
+all this; the default behavior for @code{nnmaildir} is the same as the
+default behavior for other mail back ends: articles are deleted after
+one week, etc. Except for the expiry parameters, all this
+functionality is unique to @code{nnmaildir}, so you can ignore it if
+you're just trying to duplicate the behavior you already have with
+another back end.
+
+If the value of any of these parameters is a vector, the first element
+is evaluated as a Lisp form and the result is used, rather than the
+original value. If the value is not a vector, the value itself is
+evaluated as a Lisp form. (This is why these parameters use names
+different from those of other, similar parameters supported by other
+back ends: they have different, though similar, meanings.) (For
+numbers, strings, @code{nil}, and @code{t}, you can ignore the
+@code{eval} business again; for other values, remember to use an extra
+quote and wrap the value in a vector when appropriate.)
+
+@table @code
+@item expire-age
+An integer specifying the minimum age, in seconds, of an article
+before it will be expired, or the symbol @code{never} to specify that
+articles should never be expired. If this parameter is not set,
+@code{nnmaildir} falls back to the usual
+@code{nnmail-expiry-wait}(@code{-function}) variables (the
+@code{expiry-wait} group parameter overrides @code{nnmail-expiry-wait}
+and makes @code{nnmail-expiry-wait-function} ineffective). If you
+wanted a value of 3 days, you could use something like @code{[(* 3 24
+60 60)]}; @code{nnmaildir} will evaluate the form and use the result.
+An article's age is measured starting from the article file's
+modification time. Normally, this is the same as the article's
+delivery time, but editing an article makes it younger. Moving an
+article (other than via expiry) may also make an article younger.
+
+@item expire-group
+If this is set to a string such as a full Gnus group name, like
+@example
+"backend+server.address.string:group.name"
+@end example
+and if it is not the name of the same group that the parameter belongs
+to, then articles will be moved to the specified group during expiry
+before being deleted. @emph{If this is set to an @code{nnmaildir}
+group, the article will be just as old in the destination group as it
+was in the source group.} So be careful with @code{expire-age} in the
+destination group. If this is set to the name of the same group that
+the parameter belongs to, then the article is not expired at all. If
+you use the vector form, the first element is evaluated once for each
+article. So that form can refer to
+@code{nnmaildir-article-file-name}, etc., to decide where to put the
+article. @emph{Even if this parameter is not set, @code{nnmaildir}
+does not fall back to the @code{expiry-target} group parameter or the
+@code{nnmail-expiry-target} variable.}
+
+@item read-only
+If this is set to @code{t}, @code{nnmaildir} will treat the articles
+in this maildir as read-only. This means: articles are not renamed
+from @file{new/} into @file{cur/}; articles are only found in
+@file{new/}, not @file{cur/}; articles are never deleted; articles
+cannot be edited. @file{new/} is expected to be a symlink to the
+@file{new/} directory of another maildir---e.g., a system-wide mailbox
+containing a mailing list of common interest. Everything in the
+maildir outside @file{new/} is @emph{not} treated as read-only, so for
+a shared mailbox, you do still need to set up your own maildir (or
+have write permission to the shared mailbox); your maildir just won't
+contain extra copies of the articles.
+
+@item directory-files
+A function with the same interface as @code{directory-files}. It is
+used to scan the directories in the maildir corresponding to this
+group to find articles. The default is the function specified by the
+server's @code{directory-files} parameter.
+
+@item distrust-Lines:
+If non-@code{nil}, @code{nnmaildir} will always count the lines of an
+article, rather than use the @code{Lines:} header field. If
+@code{nil}, the header field will be used if present.
+
+@item always-marks
+A list of mark symbols, such as @code{['(read expire)]}. Whenever
+Gnus asks @code{nnmaildir} for article marks, @code{nnmaildir} will
+say that all articles have these marks, regardless of whether the
+marks stored in the filesystem say so. This is a proof-of-concept
+feature that will probably be removed eventually; it ought to be done
+in Gnus proper, or abandoned if it's not worthwhile.
+
+@item never-marks
+A list of mark symbols, such as @code{['(tick expire)]}. Whenever
+Gnus asks @code{nnmaildir} for article marks, @code{nnmaildir} will
+say that no articles have these marks, regardless of whether the marks
+stored in the filesystem say so. @code{never-marks} overrides
+@code{always-marks}. This is a proof-of-concept feature that will
+probably be removed eventually; it ought to be done in Gnus proper, or
+abandoned if it's not worthwhile.
+
+@item nov-cache-size
+An integer specifying the size of the @acronym{NOV} memory cache. To
+speed things up, @code{nnmaildir} keeps @acronym{NOV} data in memory
+for a limited number of articles in each group. (This is probably not
+worthwhile, and will probably be removed in the future.) This
+parameter's value is noticed only the first time a group is seen after
+the server is opened---i.e., when you first start Gnus, typically.
+The @acronym{NOV} cache is never resized until the server is closed
+and reopened. The default is an estimate of the number of articles
+that would be displayed in the summary buffer: a count of articles
+that are either marked with @code{tick} or not marked with
+@code{read}, plus a little extra.
+@end table
+
+@node Article Identification
+@subsubsection Article identification
+Articles are stored in the @file{cur/} subdirectory of each maildir.
+Each article file is named like @code{uniq:info}, where @code{uniq}
+contains no colons. @code{nnmaildir} ignores, but preserves, the
+@code{:info} part. (Other maildir readers typically use this part of
+the filename to store marks.) The @code{uniq} part uniquely
+identifies the article, and is used in various places in the
+@file{.nnmaildir/} subdirectory of the maildir to store information
+about the corresponding article. The full pathname of an article is
+available in the variable @code{nnmaildir-article-file-name} after you
+request the article in the summary buffer.
+
+@node NOV Data
+@subsubsection NOV data
+An article identified by @code{uniq} has its @acronym{NOV} data (used
+to generate lines in the summary buffer) stored in
+@code{.nnmaildir/nov/uniq}. There is no
+@code{nnmaildir-generate-nov-databases} function. (There isn't much
+need for it---an article's @acronym{NOV} data is updated automatically
+when the article or @code{nnmail-extra-headers} has changed.) You can
+force @code{nnmaildir} to regenerate the @acronym{NOV} data for a
+single article simply by deleting the corresponding @acronym{NOV}
+file, but @emph{beware}: this will also cause @code{nnmaildir} to
+assign a new article number for this article, which may cause trouble
+with @code{seen} marks, the Agent, and the cache.
+
+@node Article Marks
+@subsubsection Article marks
+An article identified by @code{uniq} is considered to have the mark
+@code{flag} when the file @file{.nnmaildir/marks/flag/uniq} exists.
+When Gnus asks @code{nnmaildir} for a group's marks, @code{nnmaildir}
+looks for such files and reports the set of marks it finds. When Gnus
+asks @code{nnmaildir} to store a new set of marks, @code{nnmaildir}
+creates and deletes the corresponding files as needed. (Actually,
+rather than create a new file for each mark, it just creates hard
+links to @file{.nnmaildir/markfile}, to save inodes.)
+
+You can invent new marks by creating a new directory in
+@file{.nnmaildir/marks/}. You can tar up a maildir and remove it from
+your server, untar it later, and keep your marks. You can add and
+remove marks yourself by creating and deleting mark files. If you do
+this while Gnus is running and your @code{nnmaildir} server is open,
+it's best to exit all summary buffers for @code{nnmaildir} groups and
+type @kbd{s} in the group buffer first, and to type @kbd{g} or
+@kbd{M-g} in the group buffer afterwards. Otherwise, Gnus might not
+pick up the changes, and might undo them.
+
+
+@node Mail Folders
+@subsubsection Mail Folders
+@cindex nnfolder
+@cindex mbox folders
+@cindex mail folders
+
+@code{nnfolder} is a back end for storing each mail group in a
+separate file. Each file is in the standard Un*x mbox format.
+@code{nnfolder} will add extra headers to keep track of article
+numbers and arrival dates.
+
+Virtual server settings:
+
+@table @code
+@item nnfolder-directory
+@vindex nnfolder-directory
+All the @code{nnfolder} mail boxes will be stored under this
+directory. The default is the value of @code{message-directory}
+(whose default is @file{~/Mail})
+
+@item nnfolder-active-file
+@vindex nnfolder-active-file
+The name of the active file. The default is @file{~/Mail/active}.
+
+@item nnfolder-newsgroups-file
+@vindex nnfolder-newsgroups-file
+The name of the group descriptions file. @xref{Newsgroups File
+Format}. The default is @file{~/Mail/newsgroups}
+
+@item nnfolder-get-new-mail
+@vindex nnfolder-get-new-mail
+If non-@code{nil}, @code{nnfolder} will read incoming mail. The
+default is @code{t}
+
+@item nnfolder-save-buffer-hook
+@vindex nnfolder-save-buffer-hook
+@cindex backup files
+Hook run before saving the folders. Note that Emacs does the normal
+backup renaming of files even with the @code{nnfolder} buffers. If
+you wish to switch this off, you could say something like the
+following in your @file{.emacs} file:
+
+@lisp
+(defun turn-off-backup ()
+ (set (make-local-variable 'backup-inhibited) t))
+
+(add-hook 'nnfolder-save-buffer-hook 'turn-off-backup)
+@end lisp
+
+@item nnfolder-delete-mail-hook
+@vindex nnfolder-delete-mail-hook
+Hook run in a buffer narrowed to the message that is to be deleted.
+This function can be used to copy the message to somewhere else, or to
+extract some information from it before removing it.
+
+@item nnfolder-nov-is-evil
+@vindex nnfolder-nov-is-evil
+If non-@code{nil}, this back end will ignore any @acronym{NOV} files. The
+default is @code{nil}.
+
+@item nnfolder-nov-file-suffix
+@vindex nnfolder-nov-file-suffix
+The extension for @acronym{NOV} files. The default is @file{.nov}.
+
+@item nnfolder-nov-directory
+@vindex nnfolder-nov-directory
+The directory where the @acronym{NOV} files should be stored. If
+@code{nil}, @code{nnfolder-directory} is used.
+
+@end table
+
+
+@findex nnfolder-generate-active-file
+@kindex M-x nnfolder-generate-active-file
+If you have lots of @code{nnfolder}-like files you'd like to read with
+@code{nnfolder}, you can use the @kbd{M-x nnfolder-generate-active-file}
+command to make @code{nnfolder} aware of all likely files in
+@code{nnfolder-directory}. This only works if you use long file names,
+though.
+
+@node Comparing Mail Back Ends
+@subsubsection Comparing Mail Back Ends
+
+First, just for terminology, the @dfn{back end} is the common word for a
+low-level access method---a transport, if you will, by which something
+is acquired. The sense is that one's mail has to come from somewhere,
+and so selection of a suitable back end is required in order to get that
+mail within spitting distance of Gnus.
+
+The same concept exists for Usenet itself: Though access to articles is
+typically done by @acronym{NNTP} these days, once upon a midnight dreary, everyone
+in the world got at Usenet by running a reader on the machine where the
+articles lay (the machine which today we call an @acronym{NNTP} server), and
+access was by the reader stepping into the articles' directory spool
+area directly. One can still select between either the @code{nntp} or
+@code{nnspool} back ends, to select between these methods, if one happens
+actually to live on the server (or can see its spool directly, anyway,
+via NFS).
+
+The goal in selecting a mail back end is to pick one which
+simultaneously represents a suitable way of dealing with the original
+format plus leaving mail in a form that is convenient to use in the
+future. Here are some high and low points on each:
+
+@table @code
+@item nnmbox
+
+UNIX systems have historically had a single, very common, and well-defined
+format. All messages arrive in a single @dfn{spool file}, and
+they are delineated by a line whose regular expression matches
+@samp{^From_}. (My notational use of @samp{_} is to indicate a space,
+to make it clear in this instance that this is not the RFC-specified
+@samp{From:} header.) Because Emacs and therefore Gnus emanate
+historically from the Unix environment, it is simplest if one does not
+mess a great deal with the original mailbox format, so if one chooses
+this back end, Gnus' primary activity in getting mail from the real spool
+area to Gnus' preferred directory is simply to copy it, with no
+(appreciable) format change in the process. It is the ``dumbest'' way
+to move mail into availability in the Gnus environment. This makes it
+fast to move into place, but slow to parse, when Gnus has to look at
+what's where.
+
+@item nnbabyl
+
+Once upon a time, there was the DEC-10 and DEC-20, running operating
+systems called TOPS and related things, and the usual (only?) mail
+reading environment was a thing called Babyl. I don't know what format
+was used for mail landing on the system, but Babyl had its own internal
+format to which mail was converted, primarily involving creating a
+spool-file-like entity with a scheme for inserting Babyl-specific
+headers and status bits above the top of each message in the file.
+Rmail was Emacs's first mail reader, it was written by Richard Stallman,
+and Stallman came out of that TOPS/Babyl environment, so he wrote Rmail
+to understand the mail files folks already had in existence. Gnus (and
+VM, for that matter) continue to support this format because it's
+perceived as having some good qualities in those mailer-specific
+headers/status bits stuff. Rmail itself still exists as well, of
+course, and is still maintained within Emacs. Since Emacs 23, it
+uses standard mbox format rather than Babyl.
+
+Both of the above forms leave your mail in a single file on your
+file system, and they must parse that entire file each time you take a
+look at your mail.
+
+@item nnml
+
+@code{nnml} is the back end which smells the most as though you were
+actually operating with an @code{nnspool}-accessed Usenet system. (In
+fact, I believe @code{nnml} actually derived from @code{nnspool} code,
+lo these years ago.) One's mail is taken from the original spool file,
+and is then cut up into individual message files, 1:1. It maintains a
+Usenet-style active file (analogous to what one finds in an INN- or
+CNews-based news system in (for instance) @file{/var/lib/news/active},
+or what is returned via the @samp{NNTP LIST} verb) and also creates
+@dfn{overview} files for efficient group entry, as has been defined for
+@acronym{NNTP} servers for some years now. It is slower in mail-splitting,
+due to the creation of lots of files, updates to the @code{nnml} active
+file, and additions to overview files on a per-message basis, but it is
+extremely fast on access because of what amounts to the indexing support
+provided by the active file and overviews.
+
+@code{nnml} costs @dfn{inodes} in a big way; that is, it soaks up the
+resource which defines available places in the file system to put new
+files. Sysadmins take a dim view of heavy inode occupation within
+tight, shared file systems. But if you live on a personal machine where
+the file system is your own and space is not at a premium, @code{nnml}
+wins big.
+
+It is also problematic using this back end if you are living in a
+FAT16-based Windows world, since much space will be wasted on all these
+tiny files.
+
+@item nnmh
+
+The Rand MH mail-reading system has been around UNIX systems for a very
+long time; it operates by splitting one's spool file of messages into
+individual files, but with little or no indexing support---@code{nnmh}
+is considered to be semantically equivalent to ``@code{nnml} without
+active file or overviews''. This is arguably the worst choice, because
+one gets the slowness of individual file creation married to the
+slowness of access parsing when learning what's new in one's groups.
+
+@item nnfolder
+
+Basically the effect of @code{nnfolder} is @code{nnmbox} (the first
+method described above) on a per-group basis. That is, @code{nnmbox}
+itself puts @emph{all} one's mail in one file; @code{nnfolder} provides a
+little bit of optimization to this so that each of one's mail groups has
+a Unix mail box file. It's faster than @code{nnmbox} because each group
+can be parsed separately, and still provides the simple Unix mail box
+format requiring minimal effort in moving the mail around. In addition,
+it maintains an ``active'' file making it much faster for Gnus to figure
+out how many messages there are in each separate group.
+
+If you have groups that are expected to have a massive amount of
+messages, @code{nnfolder} is not the best choice, but if you receive
+only a moderate amount of mail, @code{nnfolder} is probably the most
+friendly mail back end all over.
+
+@item nnmaildir
+
+For configuring expiry and other things, @code{nnmaildir} uses
+incompatible group parameters, slightly different from those of other
+mail back ends.
+
+@code{nnmaildir} is largely similar to @code{nnml}, with some notable
+differences. Each message is stored in a separate file, but the
+filename is unrelated to the article number in Gnus. @code{nnmaildir}
+also stores the equivalent of @code{nnml}'s overview files in one file
+per article, so it uses about twice as many inodes as @code{nnml}.
+(Use @code{df -i} to see how plentiful your inode supply is.) If this
+slows you down or takes up very much space, a non-block-structured
+file system.
+
+Since maildirs don't require locking for delivery, the maildirs you use
+as groups can also be the maildirs your mail is directly delivered to.
+This means you can skip Gnus' mail splitting if your mail is already
+organized into different mailboxes during delivery. A @code{directory}
+entry in @code{mail-sources} would have a similar effect, but would
+require one set of mailboxes for spooling deliveries (in mbox format,
+thus damaging message bodies), and another set to be used as groups (in
+whatever format you like). A maildir has a built-in spool, in the
+@code{new/} subdirectory. Beware that currently, mail moved from
+@code{new/} to @code{cur/} instead of via mail splitting will not
+undergo treatment such as duplicate checking.
+
+@code{nnmaildir} stores article marks for a given group in the
+corresponding maildir, in a way designed so that it's easy to manipulate
+them from outside Gnus. You can tar up a maildir, unpack it somewhere
+else, and still have your marks.
+
+@code{nnmaildir} uses a significant amount of memory to speed things up.
+(It keeps in memory some of the things that @code{nnml} stores in files
+and that @code{nnmh} repeatedly parses out of message files.) If this
+is a problem for you, you can set the @code{nov-cache-size} group
+parameter to something small (0 would probably not work, but 1 probably
+would) to make it use less memory. This caching will probably be
+removed in the future.
+
+Startup is likely to be slower with @code{nnmaildir} than with other
+back ends. Everything else is likely to be faster, depending in part
+on your file system.
+
+@code{nnmaildir} does not use @code{nnoo}, so you cannot use @code{nnoo}
+to write an @code{nnmaildir}-derived back end.
+
+@end table
+
+
+@node Browsing the Web
+@section Browsing the Web
+@cindex web
+@cindex browsing the web
+@cindex www
+@cindex http
+
+Web-based discussion forums are getting more and more popular. On many
+subjects, the web-based forums have become the most important forums,
+eclipsing the importance of mailing lists and news groups. The reason
+is easy to understand---they are friendly to new users; you just point
+and click, and there's the discussion. With mailing lists, you have to
+go through a cumbersome subscription procedure, and most people don't
+even know what a news group is.
+
+The problem with this scenario is that web browsers are not very good at
+being newsreaders. They do not keep track of what articles you've read;
+they do not allow you to score on subjects you're interested in; they do
+not allow off-line browsing; they require you to click around and drive
+you mad in the end.
+
+So---if web browsers suck at reading discussion forums, why not use Gnus
+to do it instead?
+
+Gnus has been getting a bit of a collection of back ends for providing
+interfaces to these sources.
+
+@menu
+* Archiving Mail::
+* Web Searches:: Creating groups from articles that match a string.
+* RSS:: Reading RDF site summary.
+@end menu
+
+The main caveat with all these web sources is that they probably won't
+work for a very long time. Gleaning information from the @acronym{HTML} data
+is guesswork at best, and when the layout is altered, the Gnus back end
+will fail. If you have reasonably new versions of these back ends,
+though, you should be ok.
+
+One thing all these Web methods have in common is that the Web sources
+are often down, unavailable or just plain too slow to be fun. In those
+cases, it makes a lot of sense to let the Gnus Agent (@pxref{Gnus
+Unplugged}) handle downloading articles, and then you can read them at
+leisure from your local disk. No more World Wide Wait for you.
+
+@node Archiving Mail
+@subsection Archiving Mail
+@cindex archiving mail
+@cindex backup of mail
+
+Some of the back ends, notably @code{nnml}, @code{nnfolder}, and
+@code{nnmaildir}, now actually store the article marks with each group.
+For these servers, archiving and restoring a group while preserving
+marks is fairly simple.
+
+(Preserving the group level and group parameters as well still
+requires ritual dancing and sacrifices to the @file{.newsrc.eld} deity
+though.)
+
+To archive an entire @code{nnml}, @code{nnfolder}, or @code{nnmaildir}
+server, take a recursive copy of the server directory. There is no need
+to shut down Gnus, so archiving may be invoked by @code{cron} or
+similar. You restore the data by restoring the directory tree, and
+adding a server definition pointing to that directory in Gnus. The
+@ref{Article Backlog}, @ref{Asynchronous Fetching} and other things
+might interfere with overwriting data, so you may want to shut down Gnus
+before you restore the data.
+
+@node Web Searches
+@subsection Web Searches
+@cindex nnweb
+@cindex Google
+@cindex dejanews
+@cindex gmane
+@cindex Usenet searches
+@cindex searching the Usenet
+
+It's, like, too neat to search the Usenet for articles that match a
+string, but it, like, totally @emph{sucks}, like, totally, to use one of
+those, like, Web browsers, and you, like, have to, rilly, like, look at
+the commercials, so, like, with Gnus you can do @emph{rad}, rilly,
+searches without having to use a browser.
+
+The @code{nnweb} back end allows an easy interface to the mighty search
+engine. You create an @code{nnweb} group, enter a search pattern, and
+then enter the group and read the articles like you would any normal
+group. The @kbd{G w} command in the group buffer (@pxref{Foreign
+Groups}) will do this in an easy-to-use fashion.
+
+@code{nnweb} groups don't really lend themselves to being solid
+groups---they have a very fleeting idea of article numbers. In fact,
+each time you enter an @code{nnweb} group (not even changing the search
+pattern), you are likely to get the articles ordered in a different
+manner. Not even using duplicate suppression (@pxref{Duplicate
+Suppression}) will help, since @code{nnweb} doesn't even know the
+@code{Message-ID} of the articles before reading them using some search
+engines (Google, for instance). The only possible way to keep track
+of which articles you've read is by scoring on the @code{Date}
+header---mark all articles posted before the last date you read the
+group as read.
+
+If the search engine changes its output substantially, @code{nnweb}
+won't be able to parse it and will fail. One could hardly fault the Web
+providers if they were to do this---their @emph{raison d'être} is to
+make money off of advertisements, not to provide services to the
+community. Since @code{nnweb} washes the ads off all the articles, one
+might think that the providers might be somewhat miffed. We'll see.
+
+Virtual server variables:
+
+@table @code
+@item nnweb-type
+@vindex nnweb-type
+What search engine type is being used. The currently supported types
+are @code{google}, @code{dejanews}, and @code{gmane}. Note that
+@code{dejanews} is an alias to @code{google}.
+
+@item nnweb-search
+@vindex nnweb-search
+The search string to feed to the search engine.
+
+@item nnweb-max-hits
+@vindex nnweb-max-hits
+Advisory maximum number of hits per search to display. The default is
+999.
+
+@item nnweb-type-definition
+@vindex nnweb-type-definition
+Type-to-definition alist. This alist says what @code{nnweb} should do
+with the various search engine types. The following elements must be
+present:
+
+@table @code
+@item article
+Function to decode the article and provide something that Gnus
+understands.
+
+@item map
+Function to create an article number to message header and URL alist.
+
+@item search
+Function to send the search string to the search engine.
+
+@item address
+The address the aforementioned function should send the search string
+to.
+
+@item id
+Format string URL to fetch an article by @code{Message-ID}.
+@end table
+
+@end table
+
+
+@node RSS
+@subsection RSS
+@cindex nnrss
+@cindex RSS
+
+Some web sites have an RDF Site Summary (@acronym{RSS}).
+@acronym{RSS} is a format for summarizing headlines from news related
+sites (such as BBC or CNN). But basically anything list-like can be
+presented as an @acronym{RSS} feed: weblogs, changelogs or recent
+changes to a wiki (e.g., @url{http://cliki.net/site/recent-changes}).
+
+@acronym{RSS} has a quite regular and nice interface, and it's
+possible to get the information Gnus needs to keep groups updated.
+
+Note: you had better use Emacs which supports the @code{utf-8} coding
+system because @acronym{RSS} uses UTF-8 for encoding non-@acronym{ASCII}
+text by default. It is also used by default for non-@acronym{ASCII}
+group names.
+
+@kindex G R (Group)
+Use @kbd{G R} from the group buffer to subscribe to a feed---you will be
+prompted for the location, the title and the description of the feed.
+The title, which allows any characters, will be used for the group name
+and the name of the group data file. The description can be omitted.
+
+An easy way to get started with @code{nnrss} is to say something like
+the following in the group buffer: @kbd{B nnrss RET RET y}, then
+subscribe to groups.
+
+The @code{nnrss} back end saves the group data file in
+@code{nnrss-directory} (see below) for each @code{nnrss} group. File
+names containing non-@acronym{ASCII} characters will be encoded by the
+coding system specified with the @code{nnmail-pathname-coding-system}
+variable or other. Also @xref{Non-ASCII Group Names}, for more
+information.
+
+The @code{nnrss} back end generates @samp{multipart/alternative}
+@acronym{MIME} articles in which each contains a @samp{text/plain} part
+and a @samp{text/html} part.
+
+@cindex OPML
+You can also use the following commands to import and export your
+subscriptions from a file in @acronym{OPML} format (Outline Processor
+Markup Language).
+
+@defun nnrss-opml-import file
+Prompt for an @acronym{OPML} file, and subscribe to each feed in the
+file.
+@end defun
+
+@defun nnrss-opml-export
+Write your current @acronym{RSS} subscriptions to a buffer in
+@acronym{OPML} format.
+@end defun
+
+The following @code{nnrss} variables can be altered:
+
+@table @code
+@item nnrss-directory
+@vindex nnrss-directory
+The directory where @code{nnrss} stores its files. The default is
+@file{~/News/rss/}.
+
+@item nnrss-file-coding-system
+@vindex nnrss-file-coding-system
+The coding system used when reading and writing the @code{nnrss} groups
+data files. The default is the value of
+@code{mm-universal-coding-system} (which defaults to @code{emacs-mule}
+in Emacs or @code{escape-quoted} in XEmacs).
+
+@item nnrss-ignore-article-fields
+@vindex nnrss-ignore-article-fields
+Some feeds update constantly article fields during their publications,
+e.g., to indicate the number of comments. However, if there is
+a difference between the local article and the distant one, the latter
+is considered to be new. To avoid this and discard some fields, set this
+variable to the list of fields to be ignored. The default is
+@code{'(slash:comments)}.
+
+@item nnrss-use-local
+@vindex nnrss-use-local
+@findex nnrss-generate-download-script
+If you set @code{nnrss-use-local} to @code{t}, @code{nnrss} will read
+the feeds from local files in @code{nnrss-directory}. You can use
+the command @code{nnrss-generate-download-script} to generate a
+download script using @command{wget}.
+@end table
+
+The following code may be helpful, if you want to show the description in
+the summary buffer.
+
+@lisp
+(add-to-list 'nnmail-extra-headers nnrss-description-field)
+(setq gnus-summary-line-format "%U%R%z%I%(%[%4L: %-15,15f%]%) %s%uX\n")
+
+(defun gnus-user-format-function-X (header)
+ (let ((descr
+ (assq nnrss-description-field (mail-header-extra header))))
+ (if descr (concat "\n\t" (cdr descr)) "")))
+@end lisp
+
+The following code may be useful to open an nnrss url directly from the
+summary buffer.
+
+@lisp
+(require 'browse-url)
+
+(defun browse-nnrss-url (arg)
+ (interactive "p")
+ (let ((url (assq nnrss-url-field
+ (mail-header-extra
+ (gnus-data-header
+ (assq (gnus-summary-article-number)
+ gnus-newsgroup-data))))))
+ (if url
+ (progn
+ (browse-url (cdr url))
+ (gnus-summary-mark-as-read-forward 1))
+ (gnus-summary-scroll-up arg))))
+
+(eval-after-load "gnus"
+ #'(define-key gnus-summary-mode-map
+ (kbd "<RET>") 'browse-nnrss-url))
+(add-to-list 'nnmail-extra-headers nnrss-url-field)
+@end lisp
+
+Even if you have added @samp{text/html} to the
+@code{mm-discouraged-alternatives} variable (@pxref{Display
+Customization, ,Display Customization, emacs-mime, The Emacs MIME
+Manual}) since you don't want to see @acronym{HTML} parts, it might be
+more useful especially in @code{nnrss} groups to display
+@samp{text/html} parts. Here's an example of setting
+@code{mm-discouraged-alternatives} as a group parameter (@pxref{Group
+Parameters}) in order to display @samp{text/html} parts only in
+@code{nnrss} groups:
+
+@lisp
+;; @r{Set the default value of @code{mm-discouraged-alternatives}.}
+(eval-after-load "gnus-sum"
+ '(add-to-list
+ 'gnus-newsgroup-variables
+ '(mm-discouraged-alternatives
+ . '("text/html" "image/.*"))))
+
+;; @r{Display @samp{text/html} parts in @code{nnrss} groups.}
+(add-to-list
+ 'gnus-parameters
+ '("\\`nnrss:" (mm-discouraged-alternatives nil)))
+@end lisp
+
+
+@node Other Sources
+@section Other Sources
+
+Gnus can do more than just read news or mail. The methods described
+below allow Gnus to view directories and files as if they were
+newsgroups.
+
+@menu
+* Directory Groups:: You can read a directory as if it was a newsgroup.
+* Anything Groups:: Dired? Who needs dired?
+* Document Groups:: Single files can be the basis of a group.
+* Mail-To-News Gateways:: Posting articles via mail-to-news gateways.
+* The Empty Backend:: The backend that never has any news.
+@end menu
+
+
+@node Directory Groups
+@subsection Directory Groups
+@cindex nndir
+@cindex directory groups
+
+If you have a directory that has lots of articles in separate files in
+it, you might treat it as a newsgroup. The files have to have numerical
+names, of course.
+
+This might be an opportune moment to mention @code{ange-ftp} (and its
+successor @code{efs}), that most wonderful of all wonderful Emacs
+packages. When I wrote @code{nndir}, I didn't think much about it---a
+back end to read directories. Big deal.
+
+@code{ange-ftp} changes that picture dramatically. For instance, if you
+enter the @code{ange-ftp} file name
+@file{/ftp.hpc.uh.edu:/pub/emacs/ding-list/} as the directory name,
+@code{ange-ftp} or @code{efs} will actually allow you to read this
+directory over at @samp{sina} as a newsgroup. Distributed news ahoy!
+
+@code{nndir} will use @acronym{NOV} files if they are present.
+
+@code{nndir} is a ``read-only'' back end---you can't delete or expire
+articles with this method. You can use @code{nnmh} or @code{nnml} for
+whatever you use @code{nndir} for, so you could switch to any of those
+methods if you feel the need to have a non-read-only @code{nndir}.
+
+
+@node Anything Groups
+@subsection Anything Groups
+@cindex nneething
+
+From the @code{nndir} back end (which reads a single spool-like
+directory), it's just a hop and a skip to @code{nneething}, which
+pretends that any arbitrary directory is a newsgroup. Strange, but
+true.
+
+When @code{nneething} is presented with a directory, it will scan this
+directory and assign article numbers to each file. When you enter such
+a group, @code{nneething} must create ``headers'' that Gnus can use.
+After all, Gnus is a newsreader, in case you're forgetting.
+@code{nneething} does this in a two-step process. First, it snoops each
+file in question. If the file looks like an article (i.e., the first
+few lines look like headers), it will use this as the head. If this is
+just some arbitrary file without a head (e.g., a C source file),
+@code{nneething} will cobble up a header out of thin air. It will use
+file ownership, name and date and do whatever it can with these
+elements.
+
+All this should happen automatically for you, and you will be presented
+with something that looks very much like a newsgroup. Totally like a
+newsgroup, to be precise. If you select an article, it will be displayed
+in the article buffer, just as usual.
+
+If you select a line that represents a directory, Gnus will pop you into
+a new summary buffer for this @code{nneething} group. And so on. You can
+traverse the entire disk this way, if you feel like, but remember that
+Gnus is not dired, really, and does not intend to be, either.
+
+There are two overall modes to this action---ephemeral or solid. When
+doing the ephemeral thing (i.e., @kbd{G D} from the group buffer), Gnus
+will not store information on what files you have read, and what files
+are new, and so on. If you create a solid @code{nneething} group the
+normal way with @kbd{G m}, Gnus will store a mapping table between
+article numbers and file names, and you can treat this group like any
+other groups. When you activate a solid @code{nneething} group, you will
+be told how many unread articles it contains, etc., etc.
+
+Some variables:
+
+@table @code
+@item nneething-map-file-directory
+@vindex nneething-map-file-directory
+All the mapping files for solid @code{nneething} groups will be stored
+in this directory, which defaults to @file{~/.nneething/}.
+
+@item nneething-exclude-files
+@vindex nneething-exclude-files
+All files that match this regexp will be ignored. Nice to use to exclude
+auto-save files and the like, which is what it does by default.
+
+@item nneething-include-files
+@vindex nneething-include-files
+Regexp saying what files to include in the group. If this variable is
+non-@code{nil}, only files matching this regexp will be included.
+
+@item nneething-map-file
+@vindex nneething-map-file
+Name of the map files.
+@end table
+
+
+@node Document Groups
+@subsection Document Groups
+@cindex nndoc
+@cindex documentation group
+@cindex help group
+
+@code{nndoc} is a cute little thing that will let you read a single file
+as a newsgroup. Several files types are supported:
+
+@table @code
+@cindex Babyl
+@item babyl
+The Babyl format.
+
+@cindex mbox
+@cindex Unix mbox
+@item mbox
+The standard Unix mbox file.
+
+@cindex MMDF mail box
+@item mmdf
+The MMDF mail box format.
+
+@item news
+Several news articles appended into a file.
+
+@cindex rnews batch files
+@item rnews
+The rnews batch transport format.
+
+@item nsmail
+Netscape mail boxes.
+
+@item mime-parts
+@acronym{MIME} multipart messages.
+
+@item standard-digest
+The standard (RFC 1153) digest format.
+
+@item mime-digest
+A @acronym{MIME} digest of messages.
+
+@item lanl-gov-announce
+Announcement messages from LANL Gov Announce.
+
+@cindex git commit messages
+@item git
+@code{git} commit messages.
+
+@cindex forwarded messages
+@item rfc822-forward
+A message forwarded according to RFC822.
+
+@item outlook
+The Outlook mail box.
+
+@item oe-dbx
+The Outlook Express dbx mail box.
+
+@item exim-bounce
+A bounce message from the Exim MTA.
+
+@item forward
+A message forwarded according to informal rules.
+
+@item rfc934
+An RFC934-forwarded message.
+
+@item mailman
+A mailman digest.
+
+@item clari-briefs
+A digest of Clarinet brief news items.
+
+@item slack-digest
+Non-standard digest format---matches most things, but does it badly.
+
+@item mail-in-mail
+The last resort.
+@end table
+
+You can also use the special ``file type'' @code{guess}, which means
+that @code{nndoc} will try to guess what file type it is looking at.
+@code{digest} means that @code{nndoc} should guess what digest type the
+file is.
+
+@code{nndoc} will not try to change the file or insert any extra headers into
+it---it will simply, like, let you use the file as the basis for a
+group. And that's it.
+
+If you have some old archived articles that you want to insert into your
+new & spiffy Gnus mail back end, @code{nndoc} can probably help you with
+that. Say you have an old @file{RMAIL} file with mail that you now want
+to split into your new @code{nnml} groups. You look at that file using
+@code{nndoc} (using the @kbd{G f} command in the group buffer
+(@pxref{Foreign Groups})), set the process mark on all the articles in
+the buffer (@kbd{M P b}, for instance), and then re-spool (@kbd{B r})
+using @code{nnml}. If all goes well, all the mail in the @file{RMAIL}
+file is now also stored in lots of @code{nnml} directories, and you can
+delete that pesky @file{RMAIL} file. If you have the guts!
+
+Virtual server variables:
+
+@table @code
+@item nndoc-article-type
+@vindex nndoc-article-type
+This should be one of @code{mbox}, @code{babyl}, @code{digest},
+@code{news}, @code{rnews}, @code{mmdf}, @code{forward}, @code{rfc934},
+@code{rfc822-forward}, @code{mime-parts}, @code{standard-digest},
+@code{slack-digest}, @code{clari-briefs}, @code{nsmail}, @code{outlook},
+@code{oe-dbx}, @code{mailman}, and @code{mail-in-mail} or @code{guess}.
+
+@item nndoc-post-type
+@vindex nndoc-post-type
+This variable says whether Gnus is to consider the group a news group or
+a mail group. There are two valid values: @code{mail} (the default)
+and @code{news}.
+@end table
+
+@menu
+* Document Server Internals:: How to add your own document types.
+@end menu
+
+
+@node Document Server Internals
+@subsubsection Document Server Internals
+
+Adding new document types to be recognized by @code{nndoc} isn't
+difficult. You just have to whip up a definition of what the document
+looks like, write a predicate function to recognize that document type,
+and then hook into @code{nndoc}.
+
+First, here's an example document type definition:
+
+@example
+(mmdf
+ (article-begin . "^\^A\^A\^A\^A\n")
+ (body-end . "^\^A\^A\^A\^A\n"))
+@end example
+
+The definition is simply a unique @dfn{name} followed by a series of
+regexp pseudo-variable settings. Below are the possible
+variables---don't be daunted by the number of variables; most document
+types can be defined with very few settings:
+
+@table @code
+@item first-article
+If present, @code{nndoc} will skip past all text until it finds
+something that match this regexp. All text before this will be
+totally ignored.
+
+@item article-begin
+This setting has to be present in all document type definitions. It
+says what the beginning of each article looks like. To do more
+complicated things that cannot be dealt with a simple regexp, you can
+use @code{article-begin-function} instead of this.
+
+@item article-begin-function
+If present, this should be a function that moves point to the beginning
+of each article. This setting overrides @code{article-begin}.
+
+@item head-begin
+If present, this should be a regexp that matches the head of the
+article. To do more complicated things that cannot be dealt with a
+simple regexp, you can use @code{head-begin-function} instead of this.
+
+@item head-begin-function
+If present, this should be a function that moves point to the head of
+the article. This setting overrides @code{head-begin}.
+
+@item head-end
+This should match the end of the head of the article. It defaults to
+@samp{^$}---the empty line.
+
+@item body-begin
+This should match the beginning of the body of the article. It defaults
+to @samp{^\n}. To do more complicated things that cannot be dealt with
+a simple regexp, you can use @code{body-begin-function} instead of this.
+
+@item body-begin-function
+If present, this function should move point to the beginning of the body
+of the article. This setting overrides @code{body-begin}.
+
+@item body-end
+If present, this should match the end of the body of the article. To do
+more complicated things that cannot be dealt with a simple regexp, you
+can use @code{body-end-function} instead of this.
+
+@item body-end-function
+If present, this function should move point to the end of the body of
+the article. This setting overrides @code{body-end}.
+
+@item file-begin
+If present, this should match the beginning of the file. All text
+before this regexp will be totally ignored.
+
+@item file-end
+If present, this should match the end of the file. All text after this
+regexp will be totally ignored.
+
+@end table
+
+So, using these variables @code{nndoc} is able to dissect a document
+file into a series of articles, each with a head and a body. However, a
+few more variables are needed since not all document types are all that
+news-like---variables needed to transform the head or the body into
+something that's palatable for Gnus:
+
+@table @code
+@item prepare-body-function
+If present, this function will be called when requesting an article. It
+will be called with point at the start of the body, and is useful if the
+document has encoded some parts of its contents.
+
+@item article-transform-function
+If present, this function is called when requesting an article. It's
+meant to be used for more wide-ranging transformation of both head and
+body of the article.
+
+@item generate-head-function
+If present, this function is called to generate a head that Gnus can
+understand. It is called with the article number as a parameter, and is
+expected to generate a nice head for the article in question. It is
+called when requesting the headers of all articles.
+
+@item generate-article-function
+If present, this function is called to generate an entire article that
+Gnus can understand. It is called with the article number as a
+parameter when requesting all articles.
+
+@item dissection-function
+If present, this function is called to dissect a document by itself,
+overriding @code{first-article}, @code{article-begin},
+@code{article-begin-function}, @code{head-begin},
+@code{head-begin-function}, @code{head-end}, @code{body-begin},
+@code{body-begin-function}, @code{body-end}, @code{body-end-function},
+@code{file-begin}, and @code{file-end}.
+
+@end table
+
+Let's look at the most complicated example I can come up with---standard
+digests:
+
+@example
+(standard-digest
+ (first-article . ,(concat "^" (make-string 70 ?-) "\n\n+"))
+ (article-begin . ,(concat "\n\n" (make-string 30 ?-) "\n\n+"))
+ (prepare-body-function . nndoc-unquote-dashes)
+ (body-end-function . nndoc-digest-body-end)
+ (head-end . "^ ?$")
+ (body-begin . "^ ?\n")
+ (file-end . "^End of .*digest.*[0-9].*\n\\*\\*\\|^End of.*Digest *$")
+ (subtype digest guess))
+@end example
+
+We see that all text before a 70-width line of dashes is ignored; all
+text after a line that starts with that @samp{^End of} is also ignored;
+each article begins with a 30-width line of dashes; the line separating
+the head from the body may contain a single space; and that the body is
+run through @code{nndoc-unquote-dashes} before being delivered.
+
+To hook your own document definition into @code{nndoc}, use the
+@code{nndoc-add-type} function. It takes two parameters---the first
+is the definition itself and the second (optional) parameter says
+where in the document type definition alist to put this definition.
+The alist is traversed sequentially, and
+@code{nndoc-@var{type}-type-p} is called for a given type @var{type}.
+So @code{nndoc-mmdf-type-p} is called to see whether a document is of
+@code{mmdf} type, and so on. These type predicates should return
+@code{nil} if the document is not of the correct type; @code{t} if it
+is of the correct type; and a number if the document might be of the
+correct type. A high number means high probability; a low number
+means low probability with @samp{0} being the lowest valid number.
+
+
+@node Mail-To-News Gateways
+@subsection Mail-To-News Gateways
+@cindex mail-to-news gateways
+@cindex gateways
+
+If your local @code{nntp} server doesn't allow posting, for some reason
+or other, you can post using one of the numerous mail-to-news gateways.
+The @code{nngateway} back end provides the interface.
+
+Note that you can't read anything from this back end---it can only be
+used to post with.
+
+Server variables:
+
+@table @code
+@item nngateway-address
+@vindex nngateway-address
+This is the address of the mail-to-news gateway.
+
+@item nngateway-header-transformation
+@vindex nngateway-header-transformation
+News headers often have to be transformed in some odd way or other
+for the mail-to-news gateway to accept it. This variable says what
+transformation should be called, and defaults to
+@code{nngateway-simple-header-transformation}. The function is called
+narrowed to the headers to be transformed and with one parameter---the
+gateway address.
+
+This default function just inserts a new @code{To} header based on the
+@code{Newsgroups} header and the gateway address.
+For instance, an article with this @code{Newsgroups} header:
+
+@example
+Newsgroups: alt.religion.emacs
+@end example
+
+will get this @code{To} header inserted:
+
+@example
+To: alt-religion-emacs@@GATEWAY
+@end example
+
+The following pre-defined functions exist:
+
+@findex nngateway-simple-header-transformation
+@table @code
+
+@item nngateway-simple-header-transformation
+Creates a @code{To} header that looks like
+@var{newsgroup}@@@code{nngateway-address}.
+
+@findex nngateway-mail2news-header-transformation
+
+@item nngateway-mail2news-header-transformation
+Creates a @code{To} header that looks like
+@code{nngateway-address}.
+@end table
+
+@end table
+
+Here's an example:
+
+@lisp
+(setq gnus-post-method
+ '(nngateway
+ "mail2news@@replay.com"
+ (nngateway-header-transformation
+ nngateway-mail2news-header-transformation)))
+@end lisp
+
+So, to use this, simply say something like:
+
+@lisp
+(setq gnus-post-method '(nngateway "GATEWAY.ADDRESS"))
+@end lisp
+
+
+@node The Empty Backend
+@subsection The Empty Backend
+@cindex nnnil
+
+@code{nnnil} is a backend that can be used as a placeholder if you
+have to specify a backend somewhere, but don't really want to. The
+classical example is if you don't want to have a primary select
+methods, but want to only use secondary ones:
+
+@lisp
+(setq gnus-select-method '(nnnil ""))
+(setq gnus-secondary-select-methods
+ '((nnimap "foo")
+ (nnml "")))
+@end lisp
+
+
+@node Combined Groups
+@section Combined Groups
+
+Gnus allows combining a mixture of all the other group types into bigger
+groups.
+
+@menu
+* Virtual Groups:: Combining articles from many groups.
+@end menu
+
+
+@node Virtual Groups
+@subsection Virtual Groups
+@cindex nnvirtual
+@cindex virtual groups
+@cindex merging groups
+
+An @dfn{nnvirtual group} is really nothing more than a collection of
+other groups.
+
+For instance, if you are tired of reading many small groups, you can
+put them all in one big group, and then grow tired of reading one
+big, unwieldy group. The joys of computing!
+
+You specify @code{nnvirtual} as the method. The address should be a
+regexp to match component groups.
+
+All marks in the virtual group will stick to the articles in the
+component groups. So if you tick an article in a virtual group, the
+article will also be ticked in the component group from whence it
+came. (And vice versa---marks from the component groups will also be
+shown in the virtual group.). To create an empty virtual group, run
+@kbd{G V} (@code{gnus-group-make-empty-virtual}) in the group buffer
+and edit the method regexp with @kbd{M-e}
+(@code{gnus-group-edit-group-method})
+
+Here's an example @code{nnvirtual} method that collects all Andrea Dworkin
+newsgroups into one, big, happy newsgroup:
+
+@lisp
+(nnvirtual "^alt\\.fan\\.andrea-dworkin$\\|^rec\\.dworkin.*")
+@end lisp
+
+The component groups can be native or foreign; everything should work
+smoothly, but if your computer explodes, it was probably my fault.
+
+Collecting the same group from several servers might actually be a good
+idea if users have set the Distribution header to limit distribution.
+If you would like to read @samp{soc.motss} both from a server in Japan
+and a server in Norway, you could use the following as the group regexp:
+
+@example
+"^nntp\\+server\\.jp:soc\\.motss$\\|^nntp\\+server\\.no:soc\\.motss$"
+@end example
+
+(Remember, though, that if you're creating the group with @kbd{G m}, you
+shouldn't double the backslashes, and you should leave off the quote
+characters at the beginning and the end of the string.)
+
+This should work kinda smoothly---all articles from both groups should
+end up in this one, and there should be no duplicates. Threading (and
+the rest) will still work as usual, but there might be problems with the
+sequence of articles. Sorting on date might be an option here
+(@pxref{Selecting a Group}).
+
+One limitation, however---all groups included in a virtual
+group have to be alive (i.e., subscribed or unsubscribed). Killed or
+zombie groups can't be component groups for @code{nnvirtual} groups.
+
+@vindex nnvirtual-always-rescan
+If the @code{nnvirtual-always-rescan} variable is non-@code{nil} (which
+is the default), @code{nnvirtual} will always scan groups for unread
+articles when entering a virtual group. If this variable is @code{nil}
+and you read articles in a component group after the virtual group has
+been activated, the read articles from the component group will show up
+when you enter the virtual group. You'll also see this effect if you
+have two virtual groups that have a component group in common. If
+that's the case, you should set this variable to @code{t}. Or you can
+just tap @code{M-g} on the virtual group every time before you enter
+it---it'll have much the same effect.
+
+@code{nnvirtual} can have both mail and news groups as component groups.
+When responding to articles in @code{nnvirtual} groups, @code{nnvirtual}
+has to ask the back end of the component group the article comes from
+whether it is a news or mail back end. However, when you do a @kbd{^},
+there is typically no sure way for the component back end to know this,
+and in that case @code{nnvirtual} tells Gnus that the article came from a
+not-news back end. (Just to be on the safe side.)
+
+@kbd{C-c C-n} in the message buffer will insert the @code{Newsgroups}
+line from the article you respond to in these cases.
+
+@code{nnvirtual} groups do not inherit anything but articles and marks
+from component groups---group parameters, for instance, are not
+inherited.
+
+
+@node Email Based Diary
+@section Email Based Diary
+@cindex diary
+@cindex email based diary
+@cindex calendar
+
+This section describes a special mail back end called @code{nndiary},
+and its companion library @code{gnus-diary}. It is ``special'' in the
+sense that it is not meant to be one of the standard alternatives for
+reading mail with Gnus. See @ref{Choosing a Mail Back End} for that.
+Instead, it is used to treat @emph{some} of your mails in a special way,
+namely, as event reminders.
+
+Here is a typical scenario:
+
+@itemize @bullet
+@item
+You've got a date with Andy Mc Dowell or Bruce Willis (select according
+to your sexual preference) in one month. You don't want to forget it.
+@item
+So you send a ``reminder'' message (actually, a diary one) to yourself.
+@item
+You forget all about it and keep on getting and reading new mail, as usual.
+@item
+From time to time, as you type @kbd{g} in the group buffer and as the date
+is getting closer, the message will pop up again to remind you of your
+appointment, just as if it were new and unread.
+@item
+Read your ``new'' messages, this one included, and start dreaming again
+of the night you're gonna have.
+@item
+Once the date is over (you actually fell asleep just after dinner), the
+message will be automatically deleted if it is marked as expirable.
+@end itemize
+
+The Gnus Diary back end has the ability to handle regular appointments
+(that wouldn't ever be deleted) as well as punctual ones, operates as a
+real mail back end and is configurable in many ways. All of this is
+explained in the sections below.
+
+@menu
+* The NNDiary Back End:: Basic setup and usage.
+* The Gnus Diary Library:: Utility toolkit on top of nndiary.
+* Sending or Not Sending:: A final note on sending diary messages.
+@end menu
+
+
+@node The NNDiary Back End
+@subsection The NNDiary Back End
+@cindex nndiary
+@cindex the nndiary back end
+
+@code{nndiary} is a back end very similar to @code{nnml} (@pxref{Mail
+Spool}). Actually, it could appear as a mix of @code{nnml} and
+@code{nndraft}. If you know @code{nnml}, you're already familiar with
+the message storing scheme of @code{nndiary}: one file per message, one
+directory per group.
+
+ Before anything, there is one requirement to be able to run
+@code{nndiary} properly: you @emph{must} use the group timestamp feature
+of Gnus. This adds a timestamp to each group's parameters. @ref{Group
+Timestamp} to see how it's done.
+
+@menu
+* Diary Messages:: What makes a message valid for nndiary.
+* Running NNDiary:: NNDiary has two modes of operation.
+* Customizing NNDiary:: Bells and whistles.
+@end menu
+
+@node Diary Messages
+@subsubsection Diary Messages
+@cindex nndiary messages
+@cindex nndiary mails
+
+@code{nndiary} messages are just normal ones, except for the mandatory
+presence of 7 special headers. These headers are of the form
+@code{X-Diary-<something>}, @code{<something>} being one of
+@code{Minute}, @code{Hour}, @code{Dom}, @code{Month}, @code{Year},
+@code{Time-Zone} and @code{Dow}. @code{Dom} means ``Day of Month'', and
+@code{dow} means ``Day of Week''. These headers actually behave like
+crontab specifications and define the event date(s):
+
+@itemize @bullet
+@item
+For all headers except the @code{Time-Zone} one, a header value is
+either a star (meaning all possible values), or a list of fields
+(separated by a comma).
+@item
+A field is either an integer, or a range.
+@item
+A range is two integers separated by a dash.
+@item
+Possible integer values are 0--59 for @code{Minute}, 0--23 for
+@code{Hour}, 1--31 for @code{Dom}, 1--12 for @code{Month}, above 1971
+for @code{Year} and 0--6 for @code{Dow} (0 meaning Sunday).
+@item
+As a special case, a star in either @code{Dom} or @code{Dow} doesn't
+mean ``all possible values'', but ``use only the other field''. Note
+that if both are star'ed, the use of either one gives the same result.
+@item
+The @code{Time-Zone} header is special in that it can only have one
+value (@code{GMT}, for instance). A star doesn't mean ``all possible
+values'' (because it makes no sense), but ``the current local time
+zone''. Most of the time, you'll be using a star here. However, for a
+list of available time zone values, see the variable
+@code{nndiary-headers}.
+@end itemize
+
+As a concrete example, here are the diary headers to add to your message
+for specifying ``Each Monday and each 1st of month, at 12:00, 20:00,
+21:00, 22:00, 23:00 and 24:00, from 1999 to 2010'' (I'll let you find
+what to do then):
+
+@example
+X-Diary-Minute: 0
+X-Diary-Hour: 12, 20-24
+X-Diary-Dom: 1
+X-Diary-Month: *
+X-Diary-Year: 1999-2010
+X-Diary-Dow: 1
+X-Diary-Time-Zone: *
+@end example
+
+@node Running NNDiary
+@subsubsection Running NNDiary
+@cindex running nndiary
+@cindex nndiary operation modes
+
+@code{nndiary} has two modes of operation: ``traditional'' (the default)
+and ``autonomous''. In traditional mode, @code{nndiary} does not get new
+mail by itself. You have to move (@kbd{B m}) or copy (@kbd{B c}) mails
+from your primary mail back end to nndiary groups in order to handle them
+as diary messages. In autonomous mode, @code{nndiary} retrieves its own
+mail and handles it independently from your primary mail back end.
+
+One should note that Gnus is not inherently designed to allow several
+``master'' mail back ends at the same time. However, this does make
+sense with @code{nndiary}: you really want to send and receive diary
+messages to your diary groups directly. So, @code{nndiary} supports
+being sort of a ``second primary mail back end'' (to my knowledge, it is
+the only back end offering this feature). However, there is a limitation
+(which I hope to fix some day): respooling doesn't work in autonomous
+mode.
+
+In order to use @code{nndiary} in autonomous mode, you have several
+things to do:
+
+@itemize @bullet
+@item
+Allow @code{nndiary} to retrieve new mail by itself. Put the following
+line in your @file{~/.gnus.el} file:
+
+@lisp
+(setq nndiary-get-new-mail t)
+@end lisp
+@item
+You must arrange for diary messages (those containing @code{X-Diary-*}
+headers) to be split in a private folder @emph{before} Gnus treat them.
+Again, this is needed because Gnus cannot (yet ?) properly handle
+multiple primary mail back ends. Getting those messages from a separate
+source will compensate this misfeature to some extent.
+
+As an example, here's my procmailrc entry to store diary files in
+@file{~/.nndiary} (the default @code{nndiary} mail source file):
+
+@example
+:0 HD :
+* ^X-Diary
+.nndiary
+@end example
+@end itemize
+
+Once this is done, you might want to customize the following two options
+that affect the diary mail retrieval and splitting processes:
+
+@defvar nndiary-mail-sources
+This is the diary-specific replacement for the standard
+@code{mail-sources} variable. It obeys the same syntax, and defaults to
+@code{(file :path "~/.nndiary")}.
+@end defvar
+
+@defvar nndiary-split-methods
+This is the diary-specific replacement for the standard
+@code{nnmail-split-methods} variable. It obeys the same syntax.
+@end defvar
+
+ Finally, you may add a permanent @code{nndiary} virtual server
+(something like @code{(nndiary "diary")} should do) to your
+@code{gnus-secondary-select-methods}.
+
+ Hopefully, almost everything (see the TODO section in
+@file{nndiary.el}) will work as expected when you restart Gnus: in
+autonomous mode, typing @kbd{g} and @kbd{M-g} in the group buffer, will
+also get your new diary mails and split them according to your
+diary-specific rules, @kbd{F} will find your new diary groups etc.
+
+@node Customizing NNDiary
+@subsubsection Customizing NNDiary
+@cindex customizing nndiary
+@cindex nndiary customization
+
+Now that @code{nndiary} is up and running, it's time to customize it.
+The custom group is called @code{nndiary} (no, really ?!). You should
+browse it to figure out which options you'd like to tweak. The following
+two variables are probably the only ones you will want to change:
+
+@defvar nndiary-reminders
+This is the list of times when you want to be reminded of your
+appointments (e.g., 3 weeks before, then 2 days before, then 1 hour
+before and that's it). Remember that ``being reminded'' means that the
+diary message will pop up as brand new and unread again when you get new
+mail.
+@end defvar
+
+@defvar nndiary-week-starts-on-monday
+Rather self-explanatory. Otherwise, Sunday is assumed (this is the
+default).
+@end defvar
+
+
+@node The Gnus Diary Library
+@subsection The Gnus Diary Library
+@cindex gnus-diary
+@cindex the gnus diary library
+
+Using @code{nndiary} manually (I mean, writing the headers by hand and
+so on) would be rather boring. Fortunately, there is a library called
+@code{gnus-diary} written on top of @code{nndiary}, that does many
+useful things for you.
+
+ In order to use it, add the following line to your @file{~/.gnus.el} file:
+
+@lisp
+(require 'gnus-diary)
+@end lisp
+
+ Also, you shouldn't use any @code{gnus-user-format-function-[d|D]}
+(@pxref{Summary Buffer Lines}). @code{gnus-diary} provides both of these
+(sorry if you used them before).
+
+
+@menu
+* Diary Summary Line Format:: A nicer summary buffer line format.
+* Diary Articles Sorting:: A nicer way to sort messages.
+* Diary Headers Generation:: Not doing it manually.
+* Diary Group Parameters:: Not handling them manually.
+@end menu
+
+@node Diary Summary Line Format
+@subsubsection Diary Summary Line Format
+@cindex diary summary buffer line
+@cindex diary summary line format
+
+Displaying diary messages in standard summary line format (usually
+something like @samp{From Joe: Subject}) is pretty useless. Most of
+the time, you're the one who wrote the message, and you mostly want to
+see the event's date.
+
+ @code{gnus-diary} provides two supplemental user formats to be used in
+summary line formats. @code{D} corresponds to a formatted time string
+for the next occurrence of the event (e.g., ``Sat, Sep 22 01, 12:00''),
+while @code{d} corresponds to an approximate remaining time until the
+next occurrence of the event (e.g., ``in 6 months, 1 week'').
+
+ For example, here's how Joe's birthday is displayed in my
+@code{nndiary+diary:birthdays} summary buffer (note that the message is
+expirable, but will never be deleted, as it specifies a periodic event):
+
+@example
+ E Sat, Sep 22 01, 12:00: Joe's birthday (in 6 months, 1 week)
+@end example
+
+In order to get something like the above, you would normally add the
+following line to your diary groups'parameters:
+
+@lisp
+(gnus-summary-line-format "%U%R%z %uD: %(%s%) (%ud)\n")
+@end lisp
+
+However, @code{gnus-diary} does it automatically (@pxref{Diary Group
+Parameters}). You can however customize the provided summary line format
+with the following user options:
+
+@defvar gnus-diary-summary-line-format
+Defines the summary line format used for diary groups (@pxref{Summary
+Buffer Lines}). @code{gnus-diary} uses it to automatically update the
+diary groups'parameters.
+@end defvar
+
+@defvar gnus-diary-time-format
+Defines the format to display dates in diary summary buffers. This is
+used by the @code{D} user format. See the docstring for details.
+@end defvar
+
+@defvar gnus-diary-delay-format-function
+Defines the format function to use for displaying delays (remaining
+times) in diary summary buffers. This is used by the @code{d} user
+format. There are currently built-in functions for English and French;
+you can also define your own. See the docstring for details.
+@end defvar
+
+@node Diary Articles Sorting
+@subsubsection Diary Articles Sorting
+@cindex diary articles sorting
+@cindex diary summary lines sorting
+@findex gnus-summary-sort-by-schedule
+@findex gnus-thread-sort-by-schedule
+@findex gnus-article-sort-by-schedule
+
+@code{gnus-diary} provides new sorting functions (@pxref{Sorting the
+Summary Buffer} ) called @code{gnus-summary-sort-by-schedule},
+@code{gnus-thread-sort-by-schedule} and
+@code{gnus-article-sort-by-schedule}. These functions let you organize
+your diary summary buffers from the closest event to the farthest one.
+
+@code{gnus-diary} automatically installs
+@code{gnus-summary-sort-by-schedule} as a menu item in the summary
+buffer's ``sort'' menu, and the two others as the primary (hence
+default) sorting functions in the group parameters (@pxref{Diary Group
+Parameters}).
+
+@node Diary Headers Generation
+@subsubsection Diary Headers Generation
+@cindex diary headers generation
+@findex gnus-diary-check-message
+
+@code{gnus-diary} provides a function called
+@code{gnus-diary-check-message} to help you handle the @code{X-Diary-*}
+headers. This function ensures that the current message contains all the
+required diary headers, and prompts you for values or corrections if
+needed.
+
+ This function is hooked into the @code{nndiary} back end, so that
+moving or copying an article to a diary group will trigger it
+automatically. It is also bound to @kbd{C-c C-f d} in
+@code{message-mode} and @code{article-edit-mode} in order to ease the
+process of converting a usual mail to a diary one.
+
+ This function takes a prefix argument which will force prompting of
+all diary headers, regardless of their presence or validity. That way,
+you can very easily reschedule an already valid diary message, for
+instance.
+
+@node Diary Group Parameters
+@subsubsection Diary Group Parameters
+@cindex diary group parameters
+
+When you create a new diary group, or visit one, @code{gnus-diary}
+automatically checks your group parameters and if needed, sets the
+summary line format to the diary-specific value, installs the
+diary-specific sorting functions, and also adds the different
+@code{X-Diary-*} headers to the group's posting-style. It is then easier
+to send a diary message, because if you use @kbd{C-u a} or @kbd{C-u m}
+on a diary group to prepare a message, these headers will be inserted
+automatically (although not filled with proper values yet).
+
+@node Sending or Not Sending
+@subsection Sending or Not Sending
+
+Well, assuming you've read all of the above, here are two final notes on
+mail sending with @code{nndiary}:
+
+@itemize @bullet
+@item
+@code{nndiary} is a @emph{real} mail back end. You really send real diary
+messages for real. This means for instance that you can give
+appointments to anybody (provided they use Gnus and @code{nndiary}) by
+sending the diary message to them as well.
+@item
+However, since @code{nndiary} also has a @code{request-post} method, you
+can also use @kbd{C-u a} instead of @kbd{C-u m} on a diary group and the
+message won't actually be sent; just stored locally in the group. This
+comes in very handy for private appointments.
+@end itemize
+
+@node Gnus Unplugged
+@section Gnus Unplugged
+@cindex offline
+@cindex unplugged
+@cindex agent
+@cindex Gnus agent
+@cindex Gnus unplugged
+
+In olden times (ca. February '88), people used to run their newsreaders
+on big machines with permanent connections to the net. News transport
+was dealt with by news servers, and all the newsreaders had to do was to
+read news. Believe it or not.
+
+Nowadays most people read news and mail at home, and use some sort of
+modem to connect to the net. To avoid running up huge phone bills, it
+would be nice to have a way to slurp down all the news and mail, hang up
+the phone, read for several hours, and then upload any responses you
+have to make. And then you repeat the procedure.
+
+Of course, you can use news servers for doing this as well. I've used
+@code{inn} together with @code{slurp}, @code{pop} and @code{sendmail}
+for some years, but doing that's a bore. Moving the news server
+functionality up to the newsreader makes sense if you're the only person
+reading news on a machine.
+
+Setting up Gnus as an ``offline'' newsreader is quite simple. In
+fact, you don't have to configure anything as the agent is now enabled
+by default (@pxref{Agent Variables, gnus-agent}).
+
+Of course, to use it as such, you have to learn a few new commands.
+
+@menu
+* Agent Basics:: How it all is supposed to work.
+* Agent Categories:: How to tell the Gnus Agent what to download.
+* Agent Commands:: New commands for all the buffers.
+* Agent Visuals:: Ways that the agent may effect your summary buffer.
+* Agent as Cache:: The Agent is a big cache too.
+* Agent Expiry:: How to make old articles go away.
+* Agent Regeneration:: How to recover from lost connections and other accidents.
+* Agent and flags:: How the Agent maintains flags.
+* Agent and IMAP:: How to use the Agent with @acronym{IMAP}.
+* Outgoing Messages:: What happens when you post/mail something?
+* Agent Variables:: Customizing is fun.
+* Example Setup:: An example @file{~/.gnus.el} file for offline people.
+* Batching Agents:: How to fetch news from a @code{cron} job.
+* Agent Caveats:: What you think it'll do and what it does.
+@end menu
+
+
+@node Agent Basics
+@subsection Agent Basics
+
+First, let's get some terminology out of the way.
+
+The Gnus Agent is said to be @dfn{unplugged} when you have severed the
+connection to the net (and notified the Agent that this is the case).
+When the connection to the net is up again (and Gnus knows this), the
+Agent is @dfn{plugged}.
+
+The @dfn{local} machine is the one you're running on, and which isn't
+connected to the net continuously.
+
+@dfn{Downloading} means fetching things from the net to your local
+machine. @dfn{Uploading} is doing the opposite.
+
+You know that Gnus gives you all the opportunity you'd ever want for
+shooting yourself in the foot. Some people call it flexibility. Gnus
+is also customizable to a great extent, which means that the user has a
+say on how Gnus behaves. Other newsreaders might unconditionally shoot
+you in your foot, but with Gnus, you have a choice!
+
+Gnus is never really in plugged or unplugged state. Rather, it applies
+that state to each server individually. This means that some servers
+can be plugged while others can be unplugged. Additionally, some
+servers can be ignored by the Agent altogether (which means that
+they're kinda like plugged always).
+
+So when you unplug the Agent and then wonder why is Gnus opening a
+connection to the Net, the next step to do is to look whether all
+servers are agentized. If there is an unagentized server, you found
+the culprit.
+
+Another thing is the @dfn{offline} state. Sometimes, servers aren't
+reachable. When Gnus notices this, it asks you whether you want the
+server to be switched to offline state. If you say yes, then the
+server will behave somewhat as if it was unplugged, except that Gnus
+will ask you whether you want to switch it back online again.
+
+Let's take a typical Gnus session using the Agent.
+
+@itemize @bullet
+
+@item
+@findex gnus-unplugged
+You start Gnus with @code{gnus-unplugged}. This brings up the Gnus
+Agent in a disconnected state. You can read all the news that you have
+already fetched while in this mode.
+
+@item
+You then decide to see whether any new news has arrived. You connect
+your machine to the net (using PPP or whatever), and then hit @kbd{J j}
+to make Gnus become @dfn{plugged} and use @kbd{g} to check for new mail
+as usual. To check for new mail in unplugged mode (@pxref{Mail
+Source Specifiers}).
+
+@item
+You can then read the new news immediately, or you can download the
+news onto your local machine. If you want to do the latter, you press
+@kbd{g} to check if there are any new news and then @kbd{J s} to fetch
+all the eligible articles in all the groups. (To let Gnus know which
+articles you want to download, @pxref{Agent Categories}).
+
+@item
+After fetching the articles, you press @kbd{J j} to make Gnus become
+unplugged again, and you shut down the PPP thing (or whatever). And
+then you read the news offline.
+
+@item
+And then you go to step 2.
+@end itemize
+
+Here are some things you should do the first time (or so) that you use
+the Agent.
+
+@itemize @bullet
+
+@item
+Decide which servers should be covered by the Agent. If you have a mail
+back end, it would probably be nonsensical to have it covered by the
+Agent. Go to the server buffer (@kbd{^} in the group buffer) and press
+@kbd{J a} on the server (or servers) that you wish to have covered by the
+Agent (@pxref{Server Agent Commands}), or @kbd{J r} on automatically
+added servers you do not wish to have covered by the Agent. By default,
+no servers are agentized.
+
+@item
+Decide on download policy. It's fairly simple once you decide whether
+you are going to use agent categories, topic parameters, and/or group
+parameters to implement your policy. If you're new to gnus, it
+is probably best to start with a category, @xref{Agent Categories}.
+
+Both topic parameters (@pxref{Topic Parameters}) and agent categories
+(@pxref{Agent Categories}) provide for setting a policy that applies
+to multiple groups. Which you use is entirely up to you. Topic
+parameters do override categories so, if you mix the two, you'll have
+to take that into account. If you have a few groups that deviate from
+your policy, you can use group parameters (@pxref{Group Parameters}) to
+configure them.
+
+@item
+Uhm@dots{} that's it.
+@end itemize
+
+
+@node Agent Categories
+@subsection Agent Categories
+
+One of the main reasons to integrate the news transport layer into the
+newsreader is to allow greater control over what articles to download.
+There's not much point in downloading huge amounts of articles, just to
+find out that you're not interested in reading any of them. It's better
+to be somewhat more conservative in choosing what to download, and then
+mark the articles for downloading manually if it should turn out that
+you're interested in the articles anyway.
+
+One of the more effective methods for controlling what is to be
+downloaded is to create a @dfn{category} and then assign some (or all)
+groups to this category. Groups that do not belong in any other
+category belong to the @code{default} category. Gnus has its own
+buffer for creating and managing categories.
+
+If you prefer, you can also use group parameters (@pxref{Group
+Parameters}) and topic parameters (@pxref{Topic Parameters}) for an
+alternative approach to controlling the agent. The only real
+difference is that categories are specific to the agent (so there is
+less to learn) while group and topic parameters include the kitchen
+sink.
+
+Since you can set agent parameters in several different places we have
+a rule to decide which source to believe. This rule specifies that
+the parameter sources are checked in the following order: group
+parameters, topic parameters, agent category, and finally customizable
+variables. So you can mix all of these sources to produce a wide range
+of behavior, just don't blame me if you don't remember where you put
+your settings.
+
+@menu
+* Category Syntax:: What a category looks like.
+* Category Buffer:: A buffer for maintaining categories.
+* Category Variables:: Customize'r'Us.
+@end menu
+
+
+@node Category Syntax
+@subsubsection Category Syntax
+
+A category consists of a name, the list of groups belonging to the
+category, and a number of optional parameters that override the
+customizable variables. The complete list of agent parameters are
+listed below.
+
+@cindex Agent Parameters
+@table @code
+@item agent-groups
+The list of groups that are in this category.
+
+@item agent-predicate
+A predicate which (generally) gives a rough outline of which articles
+are eligible for downloading; and
+
+@item agent-score
+a score rule which (generally) gives you a finer granularity when
+deciding what articles to download. (Note that this @dfn{download
+score} is not necessarily related to normal scores.)
+
+@item agent-enable-expiration
+a boolean indicating whether the agent should expire old articles in
+this group. Most groups should be expired to conserve disk space. In
+fact, its probably safe to say that the gnus.* hierarchy contains the
+only groups that should not be expired.
+
+@item agent-days-until-old
+an integer indicating the number of days that the agent should wait
+before deciding that a read article is safe to expire.
+
+@item agent-low-score
+an integer that overrides the value of @code{gnus-agent-low-score}.
+
+@item agent-high-score
+an integer that overrides the value of @code{gnus-agent-high-score}.
+
+@item agent-short-article
+an integer that overrides the value of
+@code{gnus-agent-short-article}.
+
+@item agent-long-article
+an integer that overrides the value of @code{gnus-agent-long-article}.
+
+@item agent-enable-undownloaded-faces
+a symbol indicating whether the summary buffer should display
+undownloaded articles using the @code{gnus-summary-*-undownloaded-face}
+faces. Any symbol other than @code{nil} will enable the use of
+undownloaded faces.
+@end table
+
+The name of a category can not be changed once the category has been
+created.
+
+Each category maintains a list of groups that are exclusive members of
+that category. The exclusivity rule is automatically enforced, add a
+group to a new category and it is automatically removed from its old
+category.
+
+A predicate in its simplest form can be a single predicate such as
+@code{true} or @code{false}. These two will download every available
+article or nothing respectively. In the case of these two special
+predicates an additional score rule is superfluous.
+
+Predicates of @code{high} or @code{low} download articles in respect of
+their scores in relationship to @code{gnus-agent-high-score} and
+@code{gnus-agent-low-score} as described below.
+
+To gain even finer control of what is to be regarded eligible for
+download a predicate can consist of a number of predicates with logical
+operators sprinkled in between.
+
+Perhaps some examples are in order.
+
+Here's a simple predicate. (It's the default predicate, in fact, used
+for all groups that don't belong to any other category.)
+
+@lisp
+short
+@end lisp
+
+Quite simple, eh? This predicate is true if and only if the article is
+short (for some value of ``short'').
+
+Here's a more complex predicate:
+
+@lisp
+(or high
+ (and
+ (not low)
+ (not long)))
+@end lisp
+
+This means that an article should be downloaded if it has a high score,
+or if the score is not low and the article is not long. You get the
+drift.
+
+The available logical operators are @code{or}, @code{and} and
+@code{not}. (If you prefer, you can use the more ``C''-ish operators
+@samp{|}, @code{&} and @code{!} instead.)
+
+The following predicates are pre-defined, but if none of these fit what
+you want to do, you can write your own.
+
+When evaluating each of these predicates, the named constant will be
+bound to the value determined by calling
+@code{gnus-agent-find-parameter} on the appropriate parameter. For
+example, gnus-agent-short-article will be bound to
+@code{(gnus-agent-find-parameter group 'agent-short-article)}. This
+means that you can specify a predicate in your category then tune that
+predicate to individual groups.
+
+@table @code
+@item short
+True if the article is shorter than @code{gnus-agent-short-article}
+lines; default 100.
+
+@item long
+True if the article is longer than @code{gnus-agent-long-article}
+lines; default 200.
+
+@item low
+True if the article has a download score less than
+@code{gnus-agent-low-score}; default 0.
+
+@item high
+True if the article has a download score greater than
+@code{gnus-agent-high-score}; default 0.
+
+@item spam
+True if the Gnus Agent guesses that the article is spam. The
+heuristics may change over time, but at present it just computes a
+checksum and sees whether articles match.
+
+@item true
+Always true.
+
+@item false
+Always false.
+@end table
+
+If you want to create your own predicate function, here's what you have
+to know: The functions are called with no parameters, but the
+@code{gnus-headers} and @code{gnus-score} dynamic variables are bound to
+useful values.
+
+For example, you could decide that you don't want to download articles
+that were posted more than a certain number of days ago (e.g., posted
+more than @code{gnus-agent-expire-days} ago) you might write a function
+something along the lines of the following:
+
+@lisp
+(defun my-article-old-p ()
+ "Say whether an article is old."
+ (< (time-to-days (date-to-time (mail-header-date gnus-headers)))
+ (- (time-to-days (current-time)) gnus-agent-expire-days)))
+@end lisp
+
+with the predicate then defined as:
+
+@lisp
+(not my-article-old-p)
+@end lisp
+
+or you could append your predicate to the predefined
+@code{gnus-category-predicate-alist} in your @file{~/.gnus.el} or
+wherever.
+
+@lisp
+(require 'gnus-agent)
+(setq gnus-category-predicate-alist
+ (append gnus-category-predicate-alist
+ '((old . my-article-old-p))))
+@end lisp
+
+and simply specify your predicate as:
+
+@lisp
+(not old)
+@end lisp
+
+If/when using something like the above, be aware that there are many
+misconfigured systems/mailers out there and so an article's date is not
+always a reliable indication of when it was posted. Hell, some people
+just don't give a damn.
+
+The above predicates apply to @emph{all} the groups which belong to the
+category. However, if you wish to have a specific predicate for an
+individual group within a category, or you're just too lazy to set up a
+new category, you can enter a group's individual predicate in its group
+parameters like so:
+
+@lisp
+(agent-predicate . short)
+@end lisp
+
+This is the group/topic parameter equivalent of the agent category default.
+Note that when specifying a single word predicate like this, the
+@code{agent-predicate} specification must be in dotted pair notation.
+
+The equivalent of the longer example from above would be:
+
+@lisp
+(agent-predicate or high (and (not low) (not long)))
+@end lisp
+
+The outer parenthesis required in the category specification are not
+entered here as, not being in dotted pair notation, the value of the
+predicate is assumed to be a list.
+
+
+Now, the syntax of the download score is the same as the syntax of
+normal score files, except that all elements that require actually
+seeing the article itself are verboten. This means that only the
+following headers can be scored on: @code{Subject}, @code{From},
+@code{Date}, @code{Message-ID}, @code{References}, @code{Chars},
+@code{Lines}, and @code{Xref}.
+
+As with predicates, the specification of the @code{download score rule}
+to use in respect of a group can be in either the category definition if
+it's to be applicable to all groups in therein, or a group's parameters
+if it's to be specific to that group.
+
+In both of these places the @code{download score rule} can take one of
+three forms:
+
+@enumerate
+@item
+Score rule
+
+This has the same syntax as a normal Gnus score file except only a
+subset of scoring keywords are available as mentioned above.
+
+example:
+
+@itemize @bullet
+@item
+Category specification
+
+@lisp
+(("from"
+ ("Lars Ingebrigtsen" 1000000 nil s))
+("lines"
+ (500 -100 nil <)))
+@end lisp
+
+@item
+Group/Topic Parameter specification
+
+@lisp
+(agent-score ("from"
+ ("Lars Ingebrigtsen" 1000000 nil s))
+ ("lines"
+ (500 -100 nil <)))
+@end lisp
+
+Again, note the omission of the outermost parenthesis here.
+@end itemize
+
+@item
+Agent score file
+
+These score files must @emph{only} contain the permitted scoring
+keywords stated above.
+
+example:
+
+@itemize @bullet
+@item
+Category specification
+
+@lisp
+("~/News/agent.SCORE")
+@end lisp
+
+or perhaps
+
+@lisp
+("~/News/agent.SCORE" "~/News/agent.group.SCORE")
+@end lisp
+
+@item
+Group Parameter specification
+
+@lisp
+(agent-score "~/News/agent.SCORE")
+@end lisp
+
+Additional score files can be specified as above. Need I say anything
+about parenthesis?
+@end itemize
+
+@item
+Use @code{normal} score files
+
+If you don't want to maintain two sets of scoring rules for a group, and
+your desired @code{downloading} criteria for a group are the same as your
+@code{reading} criteria then you can tell the agent to refer to your
+@code{normal} score files when deciding what to download.
+
+These directives in either the category definition or a group's
+parameters will cause the agent to read in all the applicable score
+files for a group, @emph{filtering out} those sections that do not
+relate to one of the permitted subset of scoring keywords.
+
+@itemize @bullet
+@item
+Category Specification
+
+@lisp
+file
+@end lisp
+
+@item
+Group Parameter specification
+
+@lisp
+(agent-score . file)
+@end lisp
+@end itemize
+@end enumerate
+
+@node Category Buffer
+@subsubsection Category Buffer
+
+You'd normally do all category maintenance from the category buffer.
+When you enter it for the first time (with the @kbd{J c} command from
+the group buffer), you'll only see the @code{default} category.
+
+The following commands are available in this buffer:
+
+@table @kbd
+@item q
+@kindex q (Category)
+@findex gnus-category-exit
+Return to the group buffer (@code{gnus-category-exit}).
+
+@item e
+@kindex e (Category)
+@findex gnus-category-customize-category
+Use a customization buffer to set all of the selected category's
+parameters at one time (@code{gnus-category-customize-category}).
+
+@item k
+@kindex k (Category)
+@findex gnus-category-kill
+Kill the current category (@code{gnus-category-kill}).
+
+@item c
+@kindex c (Category)
+@findex gnus-category-copy
+Copy the current category (@code{gnus-category-copy}).
+
+@item a
+@kindex a (Category)
+@findex gnus-category-add
+Add a new category (@code{gnus-category-add}).
+
+@item p
+@kindex p (Category)
+@findex gnus-category-edit-predicate
+Edit the predicate of the current category
+(@code{gnus-category-edit-predicate}).
+
+@item g
+@kindex g (Category)
+@findex gnus-category-edit-groups
+Edit the list of groups belonging to the current category
+(@code{gnus-category-edit-groups}).
+
+@item s
+@kindex s (Category)
+@findex gnus-category-edit-score
+Edit the download score rule of the current category
+(@code{gnus-category-edit-score}).
+
+@item l
+@kindex l (Category)
+@findex gnus-category-list
+List all the categories (@code{gnus-category-list}).
+@end table
+
+
+@node Category Variables
+@subsubsection Category Variables
+
+@table @code
+@item gnus-category-mode-hook
+@vindex gnus-category-mode-hook
+Hook run in category buffers.
+
+@item gnus-category-line-format
+@vindex gnus-category-line-format
+Format of the lines in the category buffer (@pxref{Formatting
+Variables}). Valid elements are:
+
+@table @samp
+@item c
+The name of the category.
+
+@item g
+The number of groups in the category.
+@end table
+
+@item gnus-category-mode-line-format
+@vindex gnus-category-mode-line-format
+Format of the category mode line (@pxref{Mode Line Formatting}).
+
+@item gnus-agent-short-article
+@vindex gnus-agent-short-article
+Articles that have fewer lines than this are short. Default 100.
+
+@item gnus-agent-long-article
+@vindex gnus-agent-long-article
+Articles that have more lines than this are long. Default 200.
+
+@item gnus-agent-low-score
+@vindex gnus-agent-low-score
+Articles that have a score lower than this have a low score. Default
+0.
+
+@item gnus-agent-high-score
+@vindex gnus-agent-high-score
+Articles that have a score higher than this have a high score. Default
+0.
+
+@item gnus-agent-expire-days
+@vindex gnus-agent-expire-days
+The number of days that a @samp{read} article must stay in the agent's
+local disk before becoming eligible for expiration (While the name is
+the same, this doesn't mean expiring the article on the server. It
+just means deleting the local copy of the article). What is also
+important to understand is that the counter starts with the time the
+article was written to the local disk and not the time the article was
+read.
+Default 7.
+
+@item gnus-agent-enable-expiration
+@vindex gnus-agent-enable-expiration
+Determines whether articles in a group are, by default, expired or
+retained indefinitely. The default is @code{ENABLE} which means that
+you'll have to disable expiration when desired. On the other hand,
+you could set this to @code{DISABLE}. In that case, you would then
+have to enable expiration in selected groups.
+
+@end table
+
+
+@node Agent Commands
+@subsection Agent Commands
+@findex gnus-agent-toggle-plugged
+@kindex J j (Agent)
+
+All the Gnus Agent commands are on the @kbd{J} submap. The @kbd{J j}
+(@code{gnus-agent-toggle-plugged}) command works in all modes, and
+toggles the plugged/unplugged state of the Gnus Agent.
+
+
+@menu
+* Group Agent Commands:: Configure groups and fetch their contents.
+* Summary Agent Commands:: Manually select then fetch specific articles.
+* Server Agent Commands:: Select the servers that are supported by the agent.
+@end menu
+
+
+
+
+@node Group Agent Commands
+@subsubsection Group Agent Commands
+
+@table @kbd
+@item J u
+@kindex J u (Agent Group)
+@findex gnus-agent-fetch-groups
+Fetch all eligible articles in the current group
+(@code{gnus-agent-fetch-groups}).
+
+@item J c
+@kindex J c (Agent Group)
+@findex gnus-enter-category-buffer
+Enter the Agent category buffer (@code{gnus-enter-category-buffer}).
+
+@item J s
+@kindex J s (Agent Group)
+@findex gnus-agent-fetch-session
+Fetch all eligible articles in all groups
+(@code{gnus-agent-fetch-session}).
+
+@item J S
+@kindex J S (Agent Group)
+@findex gnus-group-send-queue
+Send all sendable messages in the queue group
+(@code{gnus-group-send-queue}). @xref{Drafts}.
+
+@item J a
+@kindex J a (Agent Group)
+@findex gnus-agent-add-group
+Add the current group to an Agent category
+(@code{gnus-agent-add-group}). This command understands the
+process/prefix convention (@pxref{Process/Prefix}).
+
+@item J r
+@kindex J r (Agent Group)
+@findex gnus-agent-remove-group
+Remove the current group from its category, if any
+(@code{gnus-agent-remove-group}). This command understands the
+process/prefix convention (@pxref{Process/Prefix}).
+
+@item J Y
+@kindex J Y (Agent Group)
+@findex gnus-agent-synchronize-flags
+Synchronize flags changed while unplugged with remote server, if any.
+
+
+@end table
+
+
+@node Summary Agent Commands
+@subsubsection Summary Agent Commands
+
+@table @kbd
+@item J #
+@kindex J # (Agent Summary)
+@findex gnus-agent-mark-article
+Mark the article for downloading (@code{gnus-agent-mark-article}).
+
+@item J M-#
+@kindex J M-# (Agent Summary)
+@findex gnus-agent-unmark-article
+Remove the downloading mark from the article
+(@code{gnus-agent-unmark-article}).
+
+@cindex %
+@item @@
+@kindex @@ (Agent Summary)
+@findex gnus-agent-toggle-mark
+Toggle whether to download the article
+(@code{gnus-agent-toggle-mark}). The download mark is @samp{%} by
+default.
+
+@item J c
+@kindex J c (Agent Summary)
+@findex gnus-agent-catchup
+Mark all articles as read (@code{gnus-agent-catchup}) that are neither cached, downloaded, nor downloadable.
+
+@item J S
+@kindex J S (Agent Summary)
+@findex gnus-agent-fetch-group
+Download all eligible (@pxref{Agent Categories}) articles in this group.
+(@code{gnus-agent-fetch-group}).
+
+@item J s
+@kindex J s (Agent Summary)
+@findex gnus-agent-summary-fetch-series
+Download all processable articles in this group.
+(@code{gnus-agent-summary-fetch-series}).
+
+@item J u
+@kindex J u (Agent Summary)
+@findex gnus-agent-summary-fetch-group
+Download all downloadable articles in the current group
+(@code{gnus-agent-summary-fetch-group}).
+
+@end table
+
+
+@node Server Agent Commands
+@subsubsection Server Agent Commands
+
+@table @kbd
+@item J a
+@kindex J a (Agent Server)
+@findex gnus-agent-add-server
+Add the current server to the list of servers covered by the Gnus Agent
+(@code{gnus-agent-add-server}).
+
+@item J r
+@kindex J r (Agent Server)
+@findex gnus-agent-remove-server
+Remove the current server from the list of servers covered by the Gnus
+Agent (@code{gnus-agent-remove-server}).
+
+@end table
+
+
+@node Agent Visuals
+@subsection Agent Visuals
+
+If you open a summary while unplugged and, Gnus knows from the group's
+active range that there are more articles than the headers currently
+stored in the Agent, you may see some articles whose subject looks
+something like @samp{[Undownloaded article #####]}. These are
+placeholders for the missing headers. Aside from setting a mark,
+there is not much that can be done with one of these placeholders.
+When Gnus finally gets a chance to fetch the group's headers, the
+placeholders will automatically be replaced by the actual headers.
+You can configure the summary buffer's maneuvering to skip over the
+placeholders if you care (See @code{gnus-auto-goto-ignores}).
+
+While it may be obvious to all, the only headers and articles
+available while unplugged are those headers and articles that were
+fetched into the Agent while previously plugged. To put it another
+way, ``If you forget to fetch something while plugged, you might have a
+less than satisfying unplugged session''. For this reason, the Agent
+adds two visual effects to your summary buffer. These effects display
+the download status of each article so that you always know which
+articles will be available when unplugged.
+
+The first visual effect is the @samp{%O} spec. If you customize
+@code{gnus-summary-line-format} to include this specifier, you will add
+a single character field that indicates an article's download status.
+Articles that have been fetched into either the Agent or the Cache,
+will display @code{gnus-downloaded-mark} (defaults to @samp{+}). All
+other articles will display @code{gnus-undownloaded-mark} (defaults to
+@samp{-}). If you open a group that has not been agentized, a space
+(@samp{ }) will be displayed.
+
+The second visual effect are the undownloaded faces. The faces, there
+are three indicating the article's score (low, normal, high), seem to
+result in a love/hate response from many Gnus users. The problem is
+that the face selection is controlled by a list of condition tests and
+face names (See @code{gnus-summary-highlight}). Each condition is
+tested in the order in which it appears in the list so early
+conditions have precedence over later conditions. All of this means
+that, if you tick an undownloaded article, the article will continue
+to be displayed in the undownloaded face rather than the ticked face.
+
+If you use the Agent as a cache (to avoid downloading the same article
+each time you visit it or to minimize your connection time), the
+undownloaded face will probably seem like a good idea. The reason
+being that you do all of our work (marking, reading, deleting) with
+downloaded articles so the normal faces always appear. For those
+users using the agent to improve online performance by caching the NOV
+database (most users since 5.10.2), the undownloaded faces may appear
+to be an absolutely horrible idea. The issue being that, since none
+of their articles have been fetched into the Agent, all of the
+normal faces will be obscured by the undownloaded faces.
+
+If you would like to use the undownloaded faces, you must enable the
+undownloaded faces by setting the @code{agent-enable-undownloaded-faces}
+group parameter to @code{t}. This parameter, like all other agent
+parameters, may be set on an Agent Category (@pxref{Agent Categories}),
+a Group Topic (@pxref{Topic Parameters}), or an individual group
+(@pxref{Group Parameters}).
+
+The one problem common to all users using the agent is how quickly it
+can consume disk space. If you using the agent on many groups, it is
+even more difficult to effectively recover disk space. One solution
+is the @samp{%F} format available in @code{gnus-group-line-format}.
+This format will display the actual disk space used by articles
+fetched into both the agent and cache. By knowing which groups use
+the most space, users know where to focus their efforts when ``agent
+expiring'' articles.
+
+@node Agent as Cache
+@subsection Agent as Cache
+
+When Gnus is plugged, it is not efficient to download headers or
+articles from the server again, if they are already stored in the
+Agent. So, Gnus normally only downloads headers once, and stores them
+in the Agent. These headers are later used when generating the summary
+buffer, regardless of whether you are plugged or unplugged. Articles
+are not cached in the Agent by default though (that would potentially
+consume lots of disk space), but if you have already downloaded an
+article into the Agent, Gnus will not download the article from the
+server again but use the locally stored copy instead.
+
+If you so desire, you can configure the agent (see @code{gnus-agent-cache}
+@pxref{Agent Variables}) to always download headers and articles while
+plugged. Gnus will almost certainly be slower, but it will be kept
+synchronized with the server. That last point probably won't make any
+sense if you are using a nntp or nnimap back end.
+
+@node Agent Expiry
+@subsection Agent Expiry
+
+@vindex gnus-agent-expire-days
+@findex gnus-agent-expire
+@kindex M-x gnus-agent-expire
+@kindex M-x gnus-agent-expire-group
+@findex gnus-agent-expire-group
+@cindex agent expiry
+@cindex Gnus agent expiry
+@cindex expiry, in Gnus agent
+
+The Agent back end, @code{nnagent}, doesn't handle expiry. Well, at
+least it doesn't handle it like other back ends. Instead, there are
+special @code{gnus-agent-expire} and @code{gnus-agent-expire-group}
+commands that will expire all read articles that are older than
+@code{gnus-agent-expire-days} days. They can be run whenever you feel
+that you're running out of space. Neither are particularly fast or
+efficient, and it's not a particularly good idea to interrupt them (with
+@kbd{C-g} or anything else) once you've started one of them.
+
+Note that other functions might run @code{gnus-agent-expire} for you
+to keep the agent synchronized with the group.
+
+The agent parameter @code{agent-enable-expiration} may be used to
+prevent expiration in selected groups.
+
+@vindex gnus-agent-expire-all
+If @code{gnus-agent-expire-all} is non-@code{nil}, the agent
+expiration commands will expire all articles---unread, read, ticked
+and dormant. If @code{nil} (which is the default), only read articles
+are eligible for expiry, and unread, ticked and dormant articles will
+be kept indefinitely.
+
+If you find that some articles eligible for expiry are never expired,
+perhaps some Gnus Agent files are corrupted. There's are special
+commands, @code{gnus-agent-regenerate} and
+@code{gnus-agent-regenerate-group}, to fix possible problems.
+
+@node Agent Regeneration
+@subsection Agent Regeneration
+
+@cindex agent regeneration
+@cindex Gnus agent regeneration
+@cindex regeneration
+
+The local data structures used by @code{nnagent} may become corrupted
+due to certain exceptional conditions. When this happens,
+@code{nnagent} functionality may degrade or even fail. The solution
+to this problem is to repair the local data structures by removing all
+internal inconsistencies.
+
+For example, if your connection to your server is lost while
+downloaded articles into the agent, the local data structures will not
+know about articles successfully downloaded prior to the connection
+failure. Running @code{gnus-agent-regenerate} or
+@code{gnus-agent-regenerate-group} will update the data structures
+such that you don't need to download these articles a second time.
+
+@findex gnus-agent-regenerate
+@kindex M-x gnus-agent-regenerate
+The command @code{gnus-agent-regenerate} will perform
+@code{gnus-agent-regenerate-group} on every agentized group. While
+you can run @code{gnus-agent-regenerate} in any buffer, it is strongly
+recommended that you first close all summary buffers.
+
+@findex gnus-agent-regenerate-group
+@kindex M-x gnus-agent-regenerate-group
+The command @code{gnus-agent-regenerate-group} uses the local copies
+of individual articles to repair the local @acronym{NOV}(header) database. It
+then updates the internal data structures that document which articles
+are stored locally. An optional argument will mark articles in the
+agent as unread.
+
+@node Agent and flags
+@subsection Agent and flags
+
+The Agent works with any Gnus back end including those, such as
+nnimap, that store flags (read, ticked, etc.)@: on the server. Sadly,
+the Agent does not actually know which backends keep their flags in
+the backend server rather than in @file{.newsrc}. This means that the
+Agent, while unplugged or disconnected, will always record all changes
+to the flags in its own files.
+
+When you plug back in, Gnus will then check to see if you have any
+changed any flags and ask if you wish to synchronize these with the
+server. This behavior is customizable by @code{gnus-agent-synchronize-flags}.
+
+@vindex gnus-agent-synchronize-flags
+If @code{gnus-agent-synchronize-flags} is @code{nil}, the Agent will
+never automatically synchronize flags. If it is @code{ask}, which is
+the default, the Agent will check if you made any changes and if so
+ask if you wish to synchronize these when you re-connect. If it has
+any other value, all flags will be synchronized automatically.
+
+If you do not wish to synchronize flags automatically when you
+re-connect, you can do it manually with the
+@code{gnus-agent-synchronize-flags} command that is bound to @kbd{J Y}
+in the group buffer.
+
+Technical note: the synchronization algorithm does not work by ``pushing''
+all local flags to the server, but rather by incrementally updated the
+server view of flags by changing only those flags that were changed by
+the user. Thus, if you set one flag on an article, quit the group then
+re-select the group and remove the flag; the flag will be set and
+removed from the server when you ``synchronize''. The queued flag
+operations can be found in the per-server @code{flags} file in the Agent
+directory. It's emptied when you synchronize flags.
+
+@node Agent and IMAP
+@subsection Agent and IMAP
+
+The Agent works with any Gnus back end, including nnimap. However,
+since there are some conceptual differences between @acronym{NNTP} and
+@acronym{IMAP}, this section (should) provide you with some information to
+make Gnus Agent work smoother as a @acronym{IMAP} Disconnected Mode client.
+
+Some things are currently not implemented in the Agent that you'd might
+expect from a disconnected @acronym{IMAP} client, including:
+
+@itemize @bullet
+
+@item
+Copying/moving articles into nnimap groups when unplugged.
+
+@item
+Creating/deleting nnimap groups when unplugged.
+
+@end itemize
+
+@node Outgoing Messages
+@subsection Outgoing Messages
+
+By default, when Gnus is unplugged, all outgoing messages (both mail
+and news) are stored in the draft group ``queue'' (@pxref{Drafts}).
+You can view them there after posting, and edit them at will.
+
+You can control the circumstances under which outgoing mail is queued
+(see @code{gnus-agent-queue-mail}, @pxref{Agent Variables}). Outgoing
+news is always queued when Gnus is unplugged, and never otherwise.
+
+You can send the messages either from the draft group with the special
+commands available there, or you can use the @kbd{J S} command in the
+group buffer to send all the sendable messages in the draft group.
+Posting news will only work when Gnus is plugged, but you can send
+mail at any time.
+
+If sending mail while unplugged does not work for you and you worry
+about hitting @kbd{J S} by accident when unplugged, you can have Gnus
+ask you to confirm your action (see
+@code{gnus-agent-prompt-send-queue}, @pxref{Agent Variables}).
+
+@node Agent Variables
+@subsection Agent Variables
+
+@table @code
+@item gnus-agent
+@vindex gnus-agent
+Is the agent enabled? The default is @code{t}. When first enabled,
+the agent will use @code{gnus-agent-auto-agentize-methods} to
+automatically mark some back ends as agentized. You may change which
+back ends are agentized using the agent commands in the server buffer.
+
+To enter the server buffer, use the @kbd{^}
+(@code{gnus-group-enter-server-mode}) command in the group buffer.
+
+
+@item gnus-agent-directory
+@vindex gnus-agent-directory
+Where the Gnus Agent will store its files. The default is
+@file{~/News/agent/}.
+
+@item gnus-agent-handle-level
+@vindex gnus-agent-handle-level
+Groups on levels (@pxref{Group Levels}) higher than this variable will
+be ignored by the Agent. The default is @code{gnus-level-subscribed},
+which means that only subscribed group will be considered by the Agent
+by default.
+
+@item gnus-agent-plugged-hook
+@vindex gnus-agent-plugged-hook
+Hook run when connecting to the network.
+
+@item gnus-agent-unplugged-hook
+@vindex gnus-agent-unplugged-hook
+Hook run when disconnecting from the network.
+
+@item gnus-agent-fetched-hook
+@vindex gnus-agent-fetched-hook
+Hook run when finished fetching articles.
+
+@item gnus-agent-cache
+@vindex gnus-agent-cache
+Variable to control whether use the locally stored @acronym{NOV} and
+articles when plugged, e.g., essentially using the Agent as a cache.
+The default is non-@code{nil}, which means to use the Agent as a cache.
+
+@item gnus-agent-go-online
+@vindex gnus-agent-go-online
+If @code{gnus-agent-go-online} is @code{nil}, the Agent will never
+automatically switch offline servers into online status. If it is
+@code{ask}, the default, the Agent will ask if you wish to switch
+offline servers into online status when you re-connect. If it has any
+other value, all offline servers will be automatically switched into
+online status.
+
+@item gnus-agent-mark-unread-after-downloaded
+@vindex gnus-agent-mark-unread-after-downloaded
+If @code{gnus-agent-mark-unread-after-downloaded} is non-@code{nil},
+mark articles as unread after downloading. This is usually a safe
+thing to do as the newly downloaded article has obviously not been
+read. The default is @code{t}.
+
+@item gnus-agent-synchronize-flags
+@vindex gnus-agent-synchronize-flags
+If @code{gnus-agent-synchronize-flags} is @code{nil}, the Agent will
+never automatically synchronize flags. If it is @code{ask}, which is
+the default, the Agent will check if you made any changes and if so
+ask if you wish to synchronize these when you re-connect. If it has
+any other value, all flags will be synchronized automatically.
+
+@item gnus-agent-consider-all-articles
+@vindex gnus-agent-consider-all-articles
+If @code{gnus-agent-consider-all-articles} is non-@code{nil}, the
+agent will let the agent predicate decide whether articles need to be
+downloaded or not, for all articles. When @code{nil}, the default,
+the agent will only let the predicate decide whether unread articles
+are downloaded or not. If you enable this, you may also want to look
+into the agent expiry settings (@pxref{Category Variables}), so that
+the agent doesn't download articles which the agent will later expire,
+over and over again.
+
+@item gnus-agent-max-fetch-size
+@vindex gnus-agent-max-fetch-size
+The agent fetches articles into a temporary buffer prior to parsing
+them into individual files. To avoid exceeding the max. buffer size,
+the agent alternates between fetching and parsing until all articles
+have been fetched. @code{gnus-agent-max-fetch-size} provides a size
+limit to control how often the cycling occurs. A large value improves
+performance. A small value minimizes the time lost should the
+connection be lost while fetching (You may need to run
+@code{gnus-agent-regenerate-group} to update the group's state.
+However, all articles parsed prior to losing the connection will be
+available while unplugged). The default is 10M so it is unusual to
+see any cycling.
+
+@item gnus-server-unopen-status
+@vindex gnus-server-unopen-status
+Perhaps not an Agent variable, but closely related to the Agent, this
+variable says what will happen if Gnus cannot open a server. If the
+Agent is enabled, the default, @code{nil}, makes Gnus ask the user
+whether to deny the server or whether to unplug the agent. If the
+Agent is disabled, Gnus always simply deny the server. Other choices
+for this variable include @code{denied} and @code{offline} the latter
+is only valid if the Agent is used.
+
+@item gnus-auto-goto-ignores
+@vindex gnus-auto-goto-ignores
+Another variable that isn't an Agent variable, yet so closely related
+that most will look for it here, this variable tells the summary
+buffer how to maneuver around undownloaded (only headers stored in the
+agent) and unfetched (neither article nor headers stored) articles.
+
+The valid values are @code{nil} (maneuver to any article),
+@code{undownloaded} (maneuvering while unplugged ignores articles that
+have not been fetched), @code{always-undownloaded} (maneuvering always
+ignores articles that have not been fetched), @code{unfetched}
+(maneuvering ignores articles whose headers have not been fetched).
+
+@item gnus-agent-queue-mail
+@vindex gnus-agent-queue-mail
+When @code{gnus-agent-queue-mail} is @code{always}, Gnus will always
+queue mail rather than sending it straight away. When @code{t}, Gnus
+will queue mail when unplugged only. When @code{nil}, never queue
+mail. The default is @code{t}.
+
+@item gnus-agent-prompt-send-queue
+@vindex gnus-agent-prompt-send-queue
+When @code{gnus-agent-prompt-send-queue} is non-@code{nil} Gnus will
+prompt you to confirm that you really wish to proceed if you hit
+@kbd{J S} while unplugged. The default is @code{nil}.
+
+@item gnus-agent-auto-agentize-methods
+@vindex gnus-agent-auto-agentize-methods
+If you have never used the Agent before (or more technically, if
+@file{~/News/agent/lib/servers} does not exist), Gnus will
+automatically agentize a few servers for you. This variable control
+which back ends should be auto-agentized. It is typically only useful
+to agentize remote back ends. The auto-agentizing has the same effect
+as running @kbd{J a} on the servers (@pxref{Server Agent Commands}).
+If the file exist, you must manage the servers manually by adding or
+removing them, this variable is only applicable the first time you
+start Gnus. The default is @samp{nil}.
+
+@end table
+
+
+@node Example Setup
+@subsection Example Setup
+
+If you don't want to read this manual, and you have a fairly standard
+setup, you may be able to use something like the following as your
+@file{~/.gnus.el} file to get started.
+
+@lisp
+;; @r{Define how Gnus is to fetch news. We do this over @acronym{NNTP}}
+;; @r{from your ISP's server.}
+(setq gnus-select-method '(nntp "news.your-isp.com"))
+
+;; @r{Define how Gnus is to read your mail. We read mail from}
+;; @r{your ISP's @acronym{POP} server.}
+(setq mail-sources '((pop :server "pop.your-isp.com")))
+
+;; @r{Say how Gnus is to store the mail. We use nnml groups.}
+(setq gnus-secondary-select-methods '((nnml "")))
+
+;; @r{Make Gnus into an offline newsreader.}
+;; (gnus-agentize) ; @r{The obsolete setting.}
+;; (setq gnus-agent t) ; @r{Now the default.}
+@end lisp
+
+That should be it, basically. Put that in your @file{~/.gnus.el} file,
+edit to suit your needs, start up PPP (or whatever), and type @kbd{M-x
+gnus}.
+
+If this is the first time you've run Gnus, you will be subscribed
+automatically to a few default newsgroups. You'll probably want to
+subscribe to more groups, and to do that, you have to query the
+@acronym{NNTP} server for a complete list of groups with the @kbd{A A}
+command. This usually takes quite a while, but you only have to do it
+once.
+
+After reading and parsing a while, you'll be presented with a list of
+groups. Subscribe to the ones you want to read with the @kbd{u}
+command. @kbd{l} to make all the killed groups disappear after you've
+subscribe to all the groups you want to read. (@kbd{A k} will bring
+back all the killed groups.)
+
+You can now read the groups at once, or you can download the articles
+with the @kbd{J s} command. And then read the rest of this manual to
+find out which of the other gazillion things you want to customize.
+
+
+@node Batching Agents
+@subsection Batching Agents
+@findex gnus-agent-batch
+
+Having the Gnus Agent fetch articles (and post whatever messages you've
+written) is quite easy once you've gotten things set up properly. The
+following shell script will do everything that is necessary:
+
+You can run a complete batch command from the command line with the
+following incantation:
+
+@example
+#!/bin/sh
+emacs -batch -l ~/.emacs -l ~/.gnus.el -f gnus-agent-batch >/dev/null 2>&1
+@end example
+
+
+@node Agent Caveats
+@subsection Agent Caveats
+
+The Gnus Agent doesn't seem to work like most other offline
+newsreaders. Here are some common questions that some imaginary people
+may ask:
+
+@table @dfn
+@item If I read an article while plugged, do they get entered into the Agent?
+
+@strong{No}. If you want this behavior, add
+@code{gnus-agent-fetch-selected-article} to
+@code{gnus-select-article-hook}.
+
+@item If I read an article while plugged, and the article already exists in
+the Agent, will it get downloaded once more?
+
+@strong{No}, unless @code{gnus-agent-cache} is @code{nil}.
+
+@end table
+
+In short, when Gnus is unplugged, it only looks into the locally stored
+articles; when it's plugged, it talks to your ISP and may also use the
+locally stored articles.
+
+
+@node Scoring
+@chapter Scoring
+@cindex scoring
+
+Other people use @dfn{kill files}, but we here at Gnus Towers like
+scoring better than killing, so we'd rather switch than fight. They do
+something completely different as well, so sit up straight and pay
+attention!
+
+@vindex gnus-summary-mark-below
+All articles have a default score (@code{gnus-summary-default-score}),
+which is 0 by default. This score may be raised or lowered either
+interactively or by score files. Articles that have a score lower than
+@code{gnus-summary-mark-below} are marked as read.
+
+Gnus will read any @dfn{score files} that apply to the current group
+before generating the summary buffer.
+
+There are several commands in the summary buffer that insert score
+entries based on the current article. You can, for instance, ask Gnus to
+lower or increase the score of all articles with a certain subject.
+
+There are two sorts of scoring entries: Permanent and temporary.
+Temporary score entries are self-expiring entries. Any entries that are
+temporary and have not been used for, say, a week, will be removed
+silently to help keep the sizes of the score files down.
+
+@menu
+* Summary Score Commands:: Adding score entries for the current group.
+* Group Score Commands:: General score commands.
+* Score Variables:: Customize your scoring. (My, what terminology).
+* Score File Format:: What a score file may contain.
+* Score File Editing:: You can edit score files by hand as well.
+* Adaptive Scoring:: Big Sister Gnus knows what you read.
+* Home Score File:: How to say where new score entries are to go.
+* Followups To Yourself:: Having Gnus notice when people answer you.
+* Scoring On Other Headers:: Scoring on non-standard headers.
+* Scoring Tips:: How to score effectively.
+* Reverse Scoring:: That problem child of old is not problem.
+* Global Score Files:: Earth-spanning, ear-splitting score files.
+* Kill Files:: They are still here, but they can be ignored.
+* Converting Kill Files:: Translating kill files to score files.
+* Advanced Scoring:: Using logical expressions to build score rules.
+* Score Decays:: It can be useful to let scores wither away.
+@end menu
+
+
+@node Summary Score Commands
+@section Summary Score Commands
+@cindex score commands
+
+The score commands that alter score entries do not actually modify real
+score files. That would be too inefficient. Gnus maintains a cache of
+previously loaded score files, one of which is considered the
+@dfn{current score file alist}. The score commands simply insert
+entries into this list, and upon group exit, this list is saved.
+
+The current score file is by default the group's local score file, even
+if no such score file actually exists. To insert score commands into
+some other score file (e.g., @file{all.SCORE}), you must first make this
+score file the current one.
+
+General score commands that don't actually change the score file:
+
+@table @kbd
+
+@item V s
+@kindex V s (Summary)
+@findex gnus-summary-set-score
+Set the score of the current article (@code{gnus-summary-set-score}).
+
+@item V S
+@kindex V S (Summary)
+@findex gnus-summary-current-score
+Display the score of the current article
+(@code{gnus-summary-current-score}).
+
+@item V t
+@kindex V t (Summary)
+@findex gnus-score-find-trace
+Display all score rules that have been used on the current article
+(@code{gnus-score-find-trace}). In the @file{*Score Trace*} buffer, you
+may type @kbd{e} to edit score file corresponding to the score rule on
+current line and @kbd{f} to format (@code{gnus-score-pretty-print}) the
+score file and edit it.
+
+@item V w
+@kindex V w (Summary)
+@findex gnus-score-find-favourite-words
+List words used in scoring (@code{gnus-score-find-favourite-words}).
+
+@item V R
+@kindex V R (Summary)
+@findex gnus-summary-rescore
+Run the current summary through the scoring process
+(@code{gnus-summary-rescore}). This might be useful if you're playing
+around with your score files behind Gnus' back and want to see the
+effect you're having.
+
+@item V c
+@kindex V c (Summary)
+@findex gnus-score-change-score-file
+Make a different score file the current
+(@code{gnus-score-change-score-file}).
+
+@item V e
+@kindex V e (Summary)
+@findex gnus-score-edit-current-scores
+Edit the current score file (@code{gnus-score-edit-current-scores}).
+You will be popped into a @code{gnus-score-mode} buffer (@pxref{Score
+File Editing}).
+
+@item V f
+@kindex V f (Summary)
+@findex gnus-score-edit-file
+Edit a score file and make this score file the current one
+(@code{gnus-score-edit-file}).
+
+@item V F
+@kindex V F (Summary)
+@findex gnus-score-flush-cache
+Flush the score cache (@code{gnus-score-flush-cache}). This is useful
+after editing score files.
+
+@item V C
+@kindex V C (Summary)
+@findex gnus-score-customize
+Customize a score file in a visually pleasing manner
+(@code{gnus-score-customize}).
+
+@end table
+
+The rest of these commands modify the local score file.
+
+@table @kbd
+
+@item V m
+@kindex V m (Summary)
+@findex gnus-score-set-mark-below
+Prompt for a score, and mark all articles with a score below this as
+read (@code{gnus-score-set-mark-below}).
+
+@item V x
+@kindex V x (Summary)
+@findex gnus-score-set-expunge-below
+Prompt for a score, and add a score rule to the current score file to
+expunge all articles below this score
+(@code{gnus-score-set-expunge-below}).
+@end table
+
+The keystrokes for actually making score entries follow a very regular
+pattern, so there's no need to list all the commands. (Hundreds of
+them.)
+
+@findex gnus-summary-increase-score
+@findex gnus-summary-lower-score
+
+@enumerate
+@item
+The first key is either @kbd{I} (upper case i) for increasing the score
+or @kbd{L} for lowering the score.
+@item
+The second key says what header you want to score on. The following
+keys are available:
+@table @kbd
+
+@item a
+Score on the author name.
+
+@item s
+Score on the subject line.
+
+@item x
+Score on the @code{Xref} line---i.e., the cross-posting line.
+
+@item r
+Score on the @code{References} line.
+
+@item d
+Score on the date.
+
+@item l
+Score on the number of lines.
+
+@item i
+Score on the @code{Message-ID} header.
+
+@item e
+Score on an ``extra'' header, that is, one of those in gnus-extra-headers,
+if your @acronym{NNTP} server tracks additional header data in overviews.
+
+@item f
+Score on followups---this matches the author name, and adds scores to
+the followups to this author. (Using this key leads to the creation of
+@file{ADAPT} files.)
+
+@item b
+Score on the body.
+
+@item h
+Score on the head.
+
+@item t
+Score on thread. (Using this key leads to the creation of @file{ADAPT}
+files.)
+
+@end table
+
+@item
+The third key is the match type. Which match types are valid depends on
+what headers you are scoring on.
+
+@table @code
+
+@item strings
+
+@table @kbd
+
+@item e
+Exact matching.
+
+@item s
+Substring matching.
+
+@item f
+Fuzzy matching (@pxref{Fuzzy Matching}).
+
+@item r
+Regexp matching
+@end table
+
+@item date
+@table @kbd
+
+@item b
+Before date.
+
+@item a
+After date.
+
+@item n
+This date.
+@end table
+
+@item number
+@table @kbd
+
+@item <
+Less than number.
+
+@item =
+Equal to number.
+
+@item >
+Greater than number.
+@end table
+@end table
+
+@item
+The fourth and usually final key says whether this is a temporary (i.e.,
+expiring) score entry, or a permanent (i.e., non-expiring) score entry,
+or whether it is to be done immediately, without adding to the score
+file.
+@table @kbd
+
+@item t
+Temporary score entry.
+
+@item p
+Permanent score entry.
+
+@item i
+Immediately scoring.
+@end table
+
+@item
+If you are scoring on @samp{e} (extra) headers, you will then be prompted for
+the header name on which you wish to score. This must be a header named
+in gnus-extra-headers, and @samp{TAB} completion is available.
+
+@end enumerate
+
+So, let's say you want to increase the score on the current author with
+exact matching permanently: @kbd{I a e p}. If you want to lower the
+score based on the subject line, using substring matching, and make a
+temporary score entry: @kbd{L s s t}. Pretty easy.
+
+To make things a bit more complicated, there are shortcuts. If you use
+a capital letter on either the second or third keys, Gnus will use
+defaults for the remaining one or two keystrokes. The defaults are
+``substring'' and ``temporary''. So @kbd{I A} is the same as @kbd{I a s
+t}, and @kbd{I a R} is the same as @kbd{I a r t}.
+
+These functions take both the numerical prefix and the symbolic prefix
+(@pxref{Symbolic Prefixes}). A numerical prefix says how much to lower
+(or increase) the score of the article. A symbolic prefix of @code{a}
+says to use the @file{all.SCORE} file for the command instead of the
+current score file.
+
+@vindex gnus-score-mimic-keymap
+The @code{gnus-score-mimic-keymap} says whether these commands will
+pretend they are keymaps or not.
+
+
+@node Group Score Commands
+@section Group Score Commands
+@cindex group score commands
+
+There aren't many of these as yet, I'm afraid.
+
+@table @kbd
+
+@item W e
+@kindex W e (Group)
+@findex gnus-score-edit-all-score
+Edit the apply-to-all-groups all.SCORE file. You will be popped into
+a @code{gnus-score-mode} buffer (@pxref{Score File Editing}).
+
+@item W f
+@kindex W f (Group)
+@findex gnus-score-flush-cache
+Gnus maintains a cache of score alists to avoid having to reload them
+all the time. This command will flush the cache
+(@code{gnus-score-flush-cache}).
+
+@end table
+
+You can do scoring from the command line by saying something like:
+
+@findex gnus-batch-score
+@cindex batch scoring
+@example
+$ emacs -batch -l ~/.emacs -l ~/.gnus.el -f gnus-batch-score
+@end example
+
+
+@node Score Variables
+@section Score Variables
+@cindex score variables
+
+@table @code
+
+@item gnus-use-scoring
+@vindex gnus-use-scoring
+If @code{nil}, Gnus will not check for score files, and will not, in
+general, do any score-related work. This is @code{t} by default.
+
+@item gnus-kill-killed
+@vindex gnus-kill-killed
+If this variable is @code{nil}, Gnus will never apply score files to
+articles that have already been through the kill process. While this
+may save you lots of time, it also means that if you apply a kill file
+to a group, and then change the kill file and want to run it over you
+group again to kill more articles, it won't work. You have to set this
+variable to @code{t} to do that. (It is @code{t} by default.)
+
+@item gnus-kill-files-directory
+@vindex gnus-kill-files-directory
+All kill and score files will be stored in this directory, which is
+initialized from the @env{SAVEDIR} environment variable by default.
+This is @file{~/News/} by default.
+
+@item gnus-score-file-suffix
+@vindex gnus-score-file-suffix
+Suffix to add to the group name to arrive at the score file name
+(@file{SCORE} by default.)
+
+@item gnus-score-uncacheable-files
+@vindex gnus-score-uncacheable-files
+@cindex score cache
+All score files are normally cached to avoid excessive re-loading of
+score files. However, this might make your Emacs grow big and
+bloated, so this regexp can be used to weed out score files unlikely
+to be needed again. It would be a bad idea to deny caching of
+@file{all.SCORE}, while it might be a good idea to not cache
+@file{comp.infosystems.www.authoring.misc.ADAPT}. In fact, this
+variable is @samp{ADAPT$} by default, so no adaptive score files will
+be cached.
+
+@item gnus-save-score
+@vindex gnus-save-score
+If you have really complicated score files, and do lots of batch
+scoring, then you might set this variable to @code{t}. This will make
+Gnus save the scores into the @file{.newsrc.eld} file.
+
+If you do not set this to @code{t}, then manual scores (like those set
+with @kbd{V s} (@code{gnus-summary-set-score})) will not be preserved
+across group visits.
+
+@item gnus-score-interactive-default-score
+@vindex gnus-score-interactive-default-score
+Score used by all the interactive raise/lower commands to raise/lower
+score with. Default is 1000, which may seem excessive, but this is to
+ensure that the adaptive scoring scheme gets enough room to play with.
+We don't want the small changes from the adaptive scoring to overwrite
+manually entered data.
+
+@item gnus-summary-default-score
+@vindex gnus-summary-default-score
+Default score of an article, which is 0 by default.
+
+@item gnus-summary-expunge-below
+@vindex gnus-summary-expunge-below
+Don't display the summary lines of articles that have scores lower than
+this variable. This is @code{nil} by default, which means that no
+articles will be hidden. This variable is local to the summary buffers,
+and has to be set from @code{gnus-summary-mode-hook}.
+
+@item gnus-score-over-mark
+@vindex gnus-score-over-mark
+Mark (in the third column) used for articles with a score over the
+default. Default is @samp{+}.
+
+@item gnus-score-below-mark
+@vindex gnus-score-below-mark
+Mark (in the third column) used for articles with a score below the
+default. Default is @samp{-}.
+
+@item gnus-score-find-score-files-function
+@vindex gnus-score-find-score-files-function
+Function used to find score files for the current group. This function
+is called with the name of the group as the argument.
+
+Predefined functions available are:
+@table @code
+
+@item gnus-score-find-single
+@findex gnus-score-find-single
+Only apply the group's own score file.
+
+@item gnus-score-find-bnews
+@findex gnus-score-find-bnews
+Apply all score files that match, using bnews syntax. This is the
+default. If the current group is @samp{gnu.emacs.gnus}, for instance,
+@file{all.emacs.all.SCORE}, @file{not.alt.all.SCORE} and
+@file{gnu.all.SCORE} would all apply. In short, the instances of
+@samp{all} in the score file names are translated into @samp{.*}, and
+then a regexp match is done.
+
+This means that if you have some score entries that you want to apply to
+all groups, then you put those entries in the @file{all.SCORE} file.
+
+The score files are applied in a semi-random order, although Gnus will
+try to apply the more general score files before the more specific score
+files. It does this by looking at the number of elements in the score
+file names---discarding the @samp{all} elements.
+
+@item gnus-score-find-hierarchical
+@findex gnus-score-find-hierarchical
+Apply all score files from all the parent groups. This means that you
+can't have score files like @file{all.SCORE}, but you can have
+@file{SCORE}, @file{comp.SCORE} and @file{comp.emacs.SCORE} for each
+server.
+
+@end table
+This variable can also be a list of functions. In that case, all
+these functions will be called with the group name as argument, and
+all the returned lists of score files will be applied. These
+functions can also return lists of lists of score alists directly. In
+that case, the functions that return these non-file score alists
+should probably be placed before the ``real'' score file functions, to
+ensure that the last score file returned is the local score file.
+Phu.
+
+For example, to do hierarchical scoring but use a non-server-specific
+overall score file, you could use the value
+@example
+(list (lambda (group) ("all.SCORE"))
+ 'gnus-score-find-hierarchical)
+@end example
+
+@item gnus-score-expiry-days
+@vindex gnus-score-expiry-days
+This variable says how many days should pass before an unused score file
+entry is expired. If this variable is @code{nil}, no score file entries
+are expired. It's 7 by default.
+
+@item gnus-update-score-entry-dates
+@vindex gnus-update-score-entry-dates
+If this variable is non-@code{nil}, temporary score entries that have
+been triggered (matched) will have their dates updated. (This is how Gnus
+controls expiry---all non-matched-entries will become too old while
+matched entries will stay fresh and young.) However, if you set this
+variable to @code{nil}, even matched entries will grow old and will
+have to face that oh-so grim reaper.
+
+@item gnus-score-after-write-file-function
+@vindex gnus-score-after-write-file-function
+Function called with the name of the score file just written.
+
+@item gnus-score-thread-simplify
+@vindex gnus-score-thread-simplify
+If this variable is non-@code{nil}, article subjects will be
+simplified for subject scoring purposes in the same manner as with
+threading---according to the current value of
+@code{gnus-simplify-subject-functions}. If the scoring entry uses
+@code{substring} or @code{exact} matching, the match will also be
+simplified in this manner.
+
+@end table
+
+
+@node Score File Format
+@section Score File Format
+@cindex score file format
+
+A score file is an @code{emacs-lisp} file that normally contains just a
+single form. Casual users are not expected to edit these files;
+everything can be changed from the summary buffer.
+
+Anyway, if you'd like to dig into it yourself, here's an example:
+
+@lisp
+(("from"
+ ("Lars Ingebrigtsen" -10000)
+ ("Per Abrahamsen")
+ ("larsi\\|lmi" -50000 nil R))
+ ("subject"
+ ("Ding is Badd" nil 728373))
+ ("xref"
+ ("alt.politics" -1000 728372 s))
+ ("lines"
+ (2 -100 nil <))
+ (mark 0)
+ (expunge -1000)
+ (mark-and-expunge -10)
+ (read-only nil)
+ (orphan -10)
+ (adapt t)
+ (files "/hom/larsi/News/gnu.SCORE")
+ (exclude-files "all.SCORE")
+ (local (gnus-newsgroup-auto-expire t)
+ (gnus-summary-make-false-root empty))
+ (eval (ding)))
+@end lisp
+
+This example demonstrates most score file elements. @xref{Advanced
+Scoring}, for a different approach.
+
+Even though this looks much like Lisp code, nothing here is actually
+@code{eval}ed. The Lisp reader is used to read this form, though, so it
+has to be valid syntactically, if not semantically.
+
+Six keys are supported by this alist:
+
+@table @code
+
+@item STRING
+If the key is a string, it is the name of the header to perform the
+match on. Scoring can only be performed on these eight headers:
+@code{From}, @code{Subject}, @code{References}, @code{Message-ID},
+@code{Xref}, @code{Lines}, @code{Chars} and @code{Date}. In addition to
+these headers, there are three strings to tell Gnus to fetch the entire
+article and do the match on larger parts of the article: @code{Body}
+will perform the match on the body of the article, @code{Head} will
+perform the match on the head of the article, and @code{All} will
+perform the match on the entire article. Note that using any of these
+last three keys will slow down group entry @emph{considerably}. The
+final ``header'' you can score on is @code{Followup}. These score
+entries will result in new score entries being added for all follow-ups
+to articles that matches these score entries.
+
+Following this key is an arbitrary number of score entries, where each
+score entry has one to four elements.
+@enumerate
+
+@item
+The first element is the @dfn{match element}. On most headers this will
+be a string, but on the Lines and Chars headers, this must be an
+integer.
+
+@item
+If the second element is present, it should be a number---the @dfn{score
+element}. This number should be an integer in the neginf to posinf
+interval. This number is added to the score of the article if the match
+is successful. If this element is not present, the
+@code{gnus-score-interactive-default-score} number will be used
+instead. This is 1000 by default.
+
+@item
+If the third element is present, it should be a number---the @dfn{date
+element}. This date says when the last time this score entry matched,
+which provides a mechanism for expiring the score entries. It this
+element is not present, the score entry is permanent. The date is
+represented by the number of days since December 31, 1 BCE.
+
+@item
+If the fourth element is present, it should be a symbol---the @dfn{type
+element}. This element specifies what function should be used to see
+whether this score entry matches the article. What match types that can
+be used depends on what header you wish to perform the match on.
+@table @dfn
+
+@item From, Subject, References, Xref, Message-ID
+For most header types, there are the @code{r} and @code{R} (regexp), as
+well as @code{s} and @code{S} (substring) types, and @code{e} and
+@code{E} (exact match), and @code{w} (word match) types. If this
+element is not present, Gnus will assume that substring matching should
+be used. @code{R}, @code{S}, and @code{E} differ from the others in
+that the matches will be done in a case-sensitive manner. All these
+one-letter types are really just abbreviations for the @code{regexp},
+@code{string}, @code{exact}, and @code{word} types, which you can use
+instead, if you feel like.
+
+@item Extra
+Just as for the standard string overview headers, if you are using
+gnus-extra-headers, you can score on these headers' values. In this
+case, there is a 5th element in the score entry, being the name of the
+header to be scored. The following entry is useful in your
+@file{all.SCORE} file in case of spam attacks from a single origin
+host, if your @acronym{NNTP} server tracks @samp{NNTP-Posting-Host} in
+overviews:
+
+@lisp
+("111.222.333.444" -1000 nil s
+ "NNTP-Posting-Host")
+@end lisp
+
+@item Lines, Chars
+These two headers use different match types: @code{<}, @code{>},
+@code{=}, @code{>=} and @code{<=}.
+
+These predicates are true if
+
+@example
+(PREDICATE HEADER MATCH)
+@end example
+
+evaluates to non-@code{nil}. For instance, the advanced match
+@code{("lines" 4 <)} (@pxref{Advanced Scoring}) will result in the
+following form:
+
+@lisp
+(< header-value 4)
+@end lisp
+
+Or to put it another way: When using @code{<} on @code{Lines} with 4 as
+the match, we get the score added if the article has less than 4 lines.
+(It's easy to get confused and think it's the other way around. But
+it's not. I think.)
+
+When matching on @code{Lines}, be careful because some back ends (like
+@code{nndir}) do not generate @code{Lines} header, so every article ends
+up being marked as having 0 lines. This can lead to strange results if
+you happen to lower score of the articles with few lines.
+
+@item Date
+For the Date header we have three kinda silly match types:
+@code{before}, @code{at} and @code{after}. I can't really imagine this
+ever being useful, but, like, it would feel kinda silly not to provide
+this function. Just in case. You never know. Better safe than sorry.
+Once burnt, twice shy. Don't judge a book by its cover. Never not have
+sex on a first date. (I have been told that at least one person, and I
+quote, ``found this function indispensable'', however.)
+
+@cindex ISO8601
+@cindex date
+A more useful match type is @code{regexp}. With it, you can match the
+date string using a regular expression. The date is normalized to
+ISO8601 compact format first---@var{YYYYMMDD}@code{T}@var{HHMMSS}. If
+you want to match all articles that have been posted on April 1st in
+every year, you could use @samp{....0401.........} as a match string,
+for instance. (Note that the date is kept in its original time zone, so
+this will match articles that were posted when it was April 1st where
+the article was posted from. Time zones are such wholesome fun for the
+whole family, eh?)
+
+@item Head, Body, All
+These three match keys use the same match types as the @code{From} (etc.)@:
+header uses.
+
+@item Followup
+This match key is somewhat special, in that it will match the
+@code{From} header, and affect the score of not only the matching
+articles, but also all followups to the matching articles. This allows
+you to increase the score of followups to your own articles, or
+decrease the score of followups to the articles of some known
+trouble-maker. Uses the same match types as the @code{From} header
+uses. (Using this match key will lead to creation of @file{ADAPT}
+files.)
+
+@item Thread
+This match key works along the same lines as the @code{Followup} match
+key. If you say that you want to score on a (sub-)thread started by an
+article with a @code{Message-ID} @var{x}, then you add a @samp{thread}
+match. This will add a new @samp{thread} match for each article that
+has @var{x} in its @code{References} header. (These new @samp{thread}
+matches will use the @code{Message-ID}s of these matching articles.)
+This will ensure that you can raise/lower the score of an entire thread,
+even though some articles in the thread may not have complete
+@code{References} headers. Note that using this may lead to
+nondeterministic scores of the articles in the thread. (Using this match
+key will lead to creation of @file{ADAPT} files.)
+@end table
+@end enumerate
+
+@cindex score file atoms
+@item mark
+The value of this entry should be a number. Any articles with a score
+lower than this number will be marked as read.
+
+@item expunge
+The value of this entry should be a number. Any articles with a score
+lower than this number will be removed from the summary buffer.
+
+@item mark-and-expunge
+The value of this entry should be a number. Any articles with a score
+lower than this number will be marked as read and removed from the
+summary buffer.
+
+@item thread-mark-and-expunge
+The value of this entry should be a number. All articles that belong to
+a thread that has a total score below this number will be marked as read
+and removed from the summary buffer. @code{gnus-thread-score-function}
+says how to compute the total score for a thread.
+
+@item files
+The value of this entry should be any number of file names. These files
+are assumed to be score files as well, and will be loaded the same way
+this one was.
+
+@item exclude-files
+The clue of this entry should be any number of files. These files will
+not be loaded, even though they would normally be so, for some reason or
+other.
+
+@item eval
+The value of this entry will be @code{eval}ed. This element will be
+ignored when handling global score files.
+
+@item read-only
+Read-only score files will not be updated or saved. Global score files
+should feature this atom (@pxref{Global Score Files}). (Note:
+@dfn{Global} here really means @dfn{global}; not your personal
+apply-to-all-groups score files.)
+
+@item orphan
+The value of this entry should be a number. Articles that do not have
+parents will get this number added to their scores. Imagine you follow
+some high-volume newsgroup, like @samp{comp.lang.c}. Most likely you
+will only follow a few of the threads, also want to see any new threads.
+
+You can do this with the following two score file entries:
+
+@example
+ (orphan -500)
+ (mark-and-expunge -100)
+@end example
+
+When you enter the group the first time, you will only see the new
+threads. You then raise the score of the threads that you find
+interesting (with @kbd{I T} or @kbd{I S}), and ignore (@kbd{c y}) the
+rest. Next time you enter the group, you will see new articles in the
+interesting threads, plus any new threads.
+
+I.e., the orphan score atom is for high-volume groups where a few
+interesting threads which can't be found automatically by ordinary
+scoring rules exist.
+
+@item adapt
+This entry controls the adaptive scoring. If it is @code{t}, the
+default adaptive scoring rules will be used. If it is @code{ignore}, no
+adaptive scoring will be performed on this group. If it is a list, this
+list will be used as the adaptive scoring rules. If it isn't present,
+or is something other than @code{t} or @code{ignore}, the default
+adaptive scoring rules will be used. If you want to use adaptive
+scoring on most groups, you'd set @code{gnus-use-adaptive-scoring} to
+@code{t}, and insert an @code{(adapt ignore)} in the groups where you do
+not want adaptive scoring. If you only want adaptive scoring in a few
+groups, you'd set @code{gnus-use-adaptive-scoring} to @code{nil}, and
+insert @code{(adapt t)} in the score files of the groups where you want
+it.
+
+@item adapt-file
+All adaptive score entries will go to the file named by this entry. It
+will also be applied when entering the group. This atom might be handy
+if you want to adapt on several groups at once, using the same adaptive
+file for a number of groups.
+
+@item local
+@cindex local variables
+The value of this entry should be a list of @code{(@var{var}
+@var{value})} pairs. Each @var{var} will be made buffer-local to the
+current summary buffer, and set to the value specified. This is a
+convenient, if somewhat strange, way of setting variables in some
+groups if you don't like hooks much. Note that the @var{value} won't
+be evaluated.
+@end table
+
+
+@node Score File Editing
+@section Score File Editing
+
+You normally enter all scoring commands from the summary buffer, but you
+might feel the urge to edit them by hand as well, so we've supplied you
+with a mode for that.
+
+It's simply a slightly customized @code{emacs-lisp} mode, with these
+additional commands:
+
+@table @kbd
+
+@item C-c C-c
+@kindex C-c C-c (Score)
+@findex gnus-score-edit-exit
+Save the changes you have made and return to the summary buffer
+(@code{gnus-score-edit-exit}).
+
+@item C-c C-d
+@kindex C-c C-d (Score)
+@findex gnus-score-edit-insert-date
+Insert the current date in numerical format
+(@code{gnus-score-edit-insert-date}). This is really the day number, if
+you were wondering.
+
+@item C-c C-p
+@kindex C-c C-p (Score)
+@findex gnus-score-pretty-print
+The adaptive score files are saved in an unformatted fashion. If you
+intend to read one of these files, you want to @dfn{pretty print} it
+first. This command (@code{gnus-score-pretty-print}) does that for
+you.
+
+@end table
+
+Type @kbd{M-x gnus-score-mode} to use this mode.
+
+@vindex gnus-score-mode-hook
+@code{gnus-score-menu-hook} is run in score mode buffers.
+
+In the summary buffer you can use commands like @kbd{V f}, @kbd{V e} and
+@kbd{V t} to begin editing score files.
+
+
+@node Adaptive Scoring
+@section Adaptive Scoring
+@cindex adaptive scoring
+
+If all this scoring is getting you down, Gnus has a way of making it all
+happen automatically---as if by magic. Or rather, as if by artificial
+stupidity, to be precise.
+
+@vindex gnus-use-adaptive-scoring
+When you read an article, or mark an article as read, or kill an
+article, you leave marks behind. On exit from the group, Gnus can sniff
+these marks and add score elements depending on what marks it finds.
+You turn on this ability by setting @code{gnus-use-adaptive-scoring} to
+@code{t} or @code{(line)}. If you want score adaptively on separate
+words appearing in the subjects, you should set this variable to
+@code{(word)}. If you want to use both adaptive methods, set this
+variable to @code{(word line)}.
+
+@vindex gnus-default-adaptive-score-alist
+To give you complete control over the scoring process, you can customize
+the @code{gnus-default-adaptive-score-alist} variable. For instance, it
+might look something like this:
+
+@lisp
+(setq gnus-default-adaptive-score-alist
+ '((gnus-unread-mark)
+ (gnus-ticked-mark (from 4))
+ (gnus-dormant-mark (from 5))
+ (gnus-del-mark (from -4) (subject -1))
+ (gnus-read-mark (from 4) (subject 2))
+ (gnus-expirable-mark (from -1) (subject -1))
+ (gnus-killed-mark (from -1) (subject -3))
+ (gnus-kill-file-mark)
+ (gnus-ancient-mark)
+ (gnus-low-score-mark)
+ (gnus-catchup-mark (from -1) (subject -1))))
+@end lisp
+
+As you see, each element in this alist has a mark as a key (either a
+variable name or a ``real'' mark---a character). Following this key is
+a arbitrary number of header/score pairs. If there are no header/score
+pairs following the key, no adaptive scoring will be done on articles
+that have that key as the article mark. For instance, articles with
+@code{gnus-unread-mark} in the example above will not get adaptive score
+entries.
+
+Each article can have only one mark, so just a single of these rules
+will be applied to each article.
+
+To take @code{gnus-del-mark} as an example---this alist says that all
+articles that have that mark (i.e., are marked with @samp{e}) will have a
+score entry added to lower based on the @code{From} header by -4, and
+lowered by @code{Subject} by -1. Change this to fit your prejudices.
+
+If you have marked 10 articles with the same subject with
+@code{gnus-del-mark}, the rule for that mark will be applied ten times.
+That means that that subject will get a score of ten times -1, which
+should be, unless I'm much mistaken, -10.
+
+If you have auto-expirable (mail) groups (@pxref{Expiring Mail}), all
+the read articles will be marked with the @samp{E} mark. This'll
+probably make adaptive scoring slightly impossible, so auto-expiring and
+adaptive scoring doesn't really mix very well.
+
+The headers you can score on are @code{from}, @code{subject},
+@code{message-id}, @code{references}, @code{xref}, @code{lines},
+@code{chars} and @code{date}. In addition, you can score on
+@code{followup}, which will create an adaptive score entry that matches
+on the @code{References} header using the @code{Message-ID} of the
+current article, thereby matching the following thread.
+
+If you use this scheme, you should set the score file atom @code{mark}
+to something small---like -300, perhaps, to avoid having small random
+changes result in articles getting marked as read.
+
+After using adaptive scoring for a week or so, Gnus should start to
+become properly trained and enhance the authors you like best, and kill
+the authors you like least, without you having to say so explicitly.
+
+You can control what groups the adaptive scoring is to be performed on
+by using the score files (@pxref{Score File Format}). This will also
+let you use different rules in different groups.
+
+@vindex gnus-adaptive-file-suffix
+The adaptive score entries will be put into a file where the name is the
+group name with @code{gnus-adaptive-file-suffix} appended. The default
+is @file{ADAPT}.
+
+@vindex gnus-adaptive-pretty-print
+Adaptive score files can get huge and are not meant to be edited by
+human hands. If @code{gnus-adaptive-pretty-print} is @code{nil} (the
+default) those files will not be written in a human readable way.
+
+@vindex gnus-score-exact-adapt-limit
+When doing adaptive scoring, substring or fuzzy matching would probably
+give you the best results in most cases. However, if the header one
+matches is short, the possibility for false positives is great, so if
+the length of the match is less than
+@code{gnus-score-exact-adapt-limit}, exact matching will be used. If
+this variable is @code{nil}, exact matching will always be used to avoid
+this problem.
+
+@vindex gnus-default-adaptive-word-score-alist
+As mentioned above, you can adapt either on individual words or entire
+headers. If you adapt on words, the
+@code{gnus-default-adaptive-word-score-alist} variable says what score
+each instance of a word should add given a mark.
+
+@lisp
+(setq gnus-default-adaptive-word-score-alist
+ `((,gnus-read-mark . 30)
+ (,gnus-catchup-mark . -10)
+ (,gnus-killed-mark . -20)
+ (,gnus-del-mark . -15)))
+@end lisp
+
+This is the default value. If you have adaption on words enabled, every
+word that appears in subjects of articles marked with
+@code{gnus-read-mark} will result in a score rule that increase the
+score with 30 points.
+
+@vindex gnus-default-ignored-adaptive-words
+@vindex gnus-ignored-adaptive-words
+Words that appear in the @code{gnus-default-ignored-adaptive-words} list
+will be ignored. If you wish to add more words to be ignored, use the
+@code{gnus-ignored-adaptive-words} list instead.
+
+@vindex gnus-adaptive-word-length-limit
+Some may feel that short words shouldn't count when doing adaptive
+scoring. If so, you may set @code{gnus-adaptive-word-length-limit} to
+an integer. Words shorter than this number will be ignored. This
+variable defaults to @code{nil}.
+
+@vindex gnus-adaptive-word-syntax-table
+When the scoring is done, @code{gnus-adaptive-word-syntax-table} is the
+syntax table in effect. It is similar to the standard syntax table, but
+it considers numbers to be non-word-constituent characters.
+
+@vindex gnus-adaptive-word-minimum
+If @code{gnus-adaptive-word-minimum} is set to a number, the adaptive
+word scoring process will never bring down the score of an article to
+below this number. The default is @code{nil}.
+
+@vindex gnus-adaptive-word-no-group-words
+If @code{gnus-adaptive-word-no-group-words} is set to @code{t}, gnus
+won't adaptively word score any of the words in the group name. Useful
+for groups like @samp{comp.editors.emacs}, where most of the subject
+lines contain the word @samp{emacs}.
+
+After using this scheme for a while, it might be nice to write a
+@code{gnus-psychoanalyze-user} command to go through the rules and see
+what words you like and what words you don't like. Or perhaps not.
+
+Note that the adaptive word scoring thing is highly experimental and is
+likely to change in the future. Initial impressions seem to indicate
+that it's totally useless as it stands. Some more work (involving more
+rigorous statistical methods) will have to be done to make this useful.
+
+
+@node Home Score File
+@section Home Score File
+
+The score file where new score file entries will go is called the
+@dfn{home score file}. This is normally (and by default) the score file
+for the group itself. For instance, the home score file for
+@samp{gnu.emacs.gnus} is @file{gnu.emacs.gnus.SCORE}.
+
+However, this may not be what you want. It is often convenient to share
+a common home score file among many groups---all @samp{emacs} groups
+could perhaps use the same home score file.
+
+@vindex gnus-home-score-file
+The variable that controls this is @code{gnus-home-score-file}. It can
+be:
+
+@enumerate
+@item
+A string. Then this file will be used as the home score file for all
+groups.
+
+@item
+A function. The result of this function will be used as the home score
+file. The function will be called with the name of the group as the
+parameter.
+
+@item
+A list. The elements in this list can be:
+
+@enumerate
+@item
+@code{(@var{regexp} @var{file-name})}. If the @var{regexp} matches the
+group name, the @var{file-name} will be used as the home score file.
+
+@item
+A function. If the function returns non-@code{nil}, the result will
+be used as the home score file. The function will be called with the
+name of the group as the parameter.
+
+@item
+A string. Use the string as the home score file.
+@end enumerate
+
+The list will be traversed from the beginning towards the end looking
+for matches.
+
+@end enumerate
+
+So, if you want to use just a single score file, you could say:
+
+@lisp
+(setq gnus-home-score-file
+ "my-total-score-file.SCORE")
+@end lisp
+
+If you want to use @file{gnu.SCORE} for all @samp{gnu} groups and
+@file{rec.SCORE} for all @samp{rec} groups (and so on), you can say:
+
+@findex gnus-hierarchial-home-score-file
+@lisp
+(setq gnus-home-score-file
+ 'gnus-hierarchial-home-score-file)
+@end lisp
+
+This is a ready-made function provided for your convenience.
+Other functions include
+
+@table @code
+@item gnus-current-home-score-file
+@findex gnus-current-home-score-file
+Return the ``current'' regular score file. This will make scoring
+commands add entry to the ``innermost'' matching score file.
+
+@end table
+
+If you want to have one score file for the @samp{emacs} groups and
+another for the @samp{comp} groups, while letting all other groups use
+their own home score files:
+
+@lisp
+(setq gnus-home-score-file
+ ;; @r{All groups that match the regexp @code{"\\.emacs"}}
+ '(("\\.emacs" "emacs.SCORE")
+ ;; @r{All the comp groups in one score file}
+ ("^comp" "comp.SCORE")))
+@end lisp
+
+@vindex gnus-home-adapt-file
+@code{gnus-home-adapt-file} works exactly the same way as
+@code{gnus-home-score-file}, but says what the home adaptive score file
+is instead. All new adaptive file entries will go into the file
+specified by this variable, and the same syntax is allowed.
+
+In addition to using @code{gnus-home-score-file} and
+@code{gnus-home-adapt-file}, you can also use group parameters
+(@pxref{Group Parameters}) and topic parameters (@pxref{Topic
+Parameters}) to achieve much the same. Group and topic parameters take
+precedence over this variable.
+
+
+@node Followups To Yourself
+@section Followups To Yourself
+
+Gnus offers two commands for picking out the @code{Message-ID} header in
+the current buffer. Gnus will then add a score rule that scores using
+this @code{Message-ID} on the @code{References} header of other
+articles. This will, in effect, increase the score of all articles that
+respond to the article in the current buffer. Quite useful if you want
+to easily note when people answer what you've said.
+
+@table @code
+
+@item gnus-score-followup-article
+@findex gnus-score-followup-article
+This will add a score to articles that directly follow up your own
+article.
+
+@item gnus-score-followup-thread
+@findex gnus-score-followup-thread
+This will add a score to all articles that appear in a thread ``below''
+your own article.
+@end table
+
+@vindex message-sent-hook
+These two functions are both primarily meant to be used in hooks like
+@code{message-sent-hook}, like this:
+@lisp
+(add-hook 'message-sent-hook 'gnus-score-followup-thread)
+@end lisp
+
+
+If you look closely at your own @code{Message-ID}, you'll notice that
+the first two or three characters are always the same. Here's two of
+mine:
+
+@example
+<x6u3u47icf.fsf@@eyesore.no>
+<x6sp9o7ibw.fsf@@eyesore.no>
+@end example
+
+So ``my'' ident on this machine is @samp{x6}. This can be
+exploited---the following rule will raise the score on all followups to
+myself:
+
+@lisp
+("references"
+ ("<x6[0-9a-z]+\\.fsf\\(_-_\\)?@@.*eyesore\\.no>"
+ 1000 nil r))
+@end lisp
+
+Whether it's the first two or first three characters that are ``yours''
+is system-dependent.
+
+
+@node Scoring On Other Headers
+@section Scoring On Other Headers
+@cindex scoring on other headers
+
+Gnus is quite fast when scoring the ``traditional''
+headers---@samp{From}, @samp{Subject} and so on. However, scoring
+other headers requires writing a @code{head} scoring rule, which means
+that Gnus has to request every single article from the back end to find
+matches. This takes a long time in big groups.
+
+@vindex gnus-inhibit-slow-scoring
+You can inhibit this slow scoring on headers or body by setting the
+variable @code{gnus-inhibit-slow-scoring}. If
+@code{gnus-inhibit-slow-scoring} is regexp, slow scoring is inhibited if
+the group matches the regexp. If it is @code{t}, slow scoring on it is
+inhibited for all groups.
+
+Now, there's not much you can do about the slowness for news groups, but for
+mail groups, you have greater control. In @ref{To From Newsgroups},
+it's explained in greater detail what this mechanism does, but here's
+a cookbook example for @code{nnml} on how to allow scoring on the
+@samp{To} and @samp{Cc} headers.
+
+Put the following in your @file{~/.gnus.el} file.
+
+@lisp
+(setq gnus-extra-headers '(To Cc Newsgroups Keywords)
+ nnmail-extra-headers gnus-extra-headers)
+@end lisp
+
+Restart Gnus and rebuild your @code{nnml} overview files with the
+@kbd{M-x nnml-generate-nov-databases} command. This will take a long
+time if you have much mail.
+
+Now you can score on @samp{To} and @samp{Cc} as ``extra headers'' like
+so: @kbd{I e s p To RET <your name> RET}.
+
+See? Simple.
+
+
+@node Scoring Tips
+@section Scoring Tips
+@cindex scoring tips
+
+@table @dfn
+
+@item Crossposts
+@cindex crossposts
+@cindex scoring crossposts
+If you want to lower the score of crossposts, the line to match on is
+the @code{Xref} header.
+@lisp
+("xref" (" talk.politics.misc:" -1000))
+@end lisp
+
+@item Multiple crossposts
+If you want to lower the score of articles that have been crossposted to
+more than, say, 3 groups:
+@lisp
+("xref"
+ ("[^:\n]+:[0-9]+ +[^:\n]+:[0-9]+ +[^:\n]+:[0-9]+"
+ -1000 nil r))
+@end lisp
+
+@item Matching on the body
+This is generally not a very good idea---it takes a very long time.
+Gnus actually has to fetch each individual article from the server. But
+you might want to anyway, I guess. Even though there are three match
+keys (@code{Head}, @code{Body} and @code{All}), you should choose one
+and stick with it in each score file. If you use any two, each article
+will be fetched @emph{twice}. If you want to match a bit on the
+@code{Head} and a bit on the @code{Body}, just use @code{All} for all
+the matches.
+
+@item Marking as read
+You will probably want to mark articles that have scores below a certain
+number as read. This is most easily achieved by putting the following
+in your @file{all.SCORE} file:
+@lisp
+((mark -100))
+@end lisp
+You may also consider doing something similar with @code{expunge}.
+
+@item Negated character classes
+If you say stuff like @code{[^abcd]*}, you may get unexpected results.
+That will match newlines, which might lead to, well, The Unknown. Say
+@code{[^abcd\n]*} instead.
+@end table
+
+
+@node Reverse Scoring
+@section Reverse Scoring
+@cindex reverse scoring
+
+If you want to keep just articles that have @samp{Sex with Emacs} in the
+subject header, and expunge all other articles, you could put something
+like this in your score file:
+
+@lisp
+(("subject"
+ ("Sex with Emacs" 2))
+ (mark 1)
+ (expunge 1))
+@end lisp
+
+So, you raise all articles that match @samp{Sex with Emacs} and mark the
+rest as read, and expunge them to boot.
+
+
+@node Global Score Files
+@section Global Score Files
+@cindex global score files
+
+Sure, other newsreaders have ``global kill files''. These are usually
+nothing more than a single kill file that applies to all groups, stored
+in the user's home directory. Bah! Puny, weak newsreaders!
+
+What I'm talking about here are Global Score Files. Score files from
+all over the world, from users everywhere, uniting all nations in one
+big, happy score file union! Ange-score! New and untested!
+
+@vindex gnus-global-score-files
+All you have to do to use other people's score files is to set the
+@code{gnus-global-score-files} variable. One entry for each score file,
+or each score file directory. Gnus will decide by itself what score
+files are applicable to which group.
+
+To use the score file
+@file{/ftp@@ftp.gnus.org:/pub/larsi/ding/score/soc.motss.SCORE} and
+all score files in the @file{/ftp@@ftp.some-where:/pub/score} directory,
+say this:
+
+@lisp
+(setq gnus-global-score-files
+ '("/ftp@@ftp.gnus.org:/pub/larsi/ding/score/soc.motss.SCORE"
+ "/ftp@@ftp.some-where:/pub/score/"))
+@end lisp
+
+@findex gnus-score-search-global-directories
+@noindent
+Simple, eh? Directory names must end with a @samp{/}. These
+directories are typically scanned only once during each Gnus session.
+If you feel the need to manually re-scan the remote directories, you can
+use the @code{gnus-score-search-global-directories} command.
+
+Note that, at present, using this option will slow down group entry
+somewhat. (That is---a lot.)
+
+If you want to start maintaining score files for other people to use,
+just put your score file up for anonymous ftp and announce it to the
+world. Become a retro-moderator! Participate in the retro-moderator
+wars sure to ensue, where retro-moderators battle it out for the
+sympathy of the people, luring them to use their score files on false
+premises! Yay! The net is saved!
+
+Here are some tips for the would-be retro-moderator, off the top of my
+head:
+
+@itemize @bullet
+
+@item
+Articles heavily crossposted are probably junk.
+@item
+To lower a single inappropriate article, lower by @code{Message-ID}.
+@item
+Particularly brilliant authors can be raised on a permanent basis.
+@item
+Authors that repeatedly post off-charter for the group can safely be
+lowered out of existence.
+@item
+Set the @code{mark} and @code{expunge} atoms to obliterate the nastiest
+articles completely.
+
+@item
+Use expiring score entries to keep the size of the file down. You
+should probably have a long expiry period, though, as some sites keep
+old articles for a long time.
+@end itemize
+
+@dots{} I wonder whether other newsreaders will support global score files
+in the future. @emph{Snicker}. Yup, any day now, newsreaders like Blue
+Wave, xrn and 1stReader are bound to implement scoring. Should we start
+holding our breath yet?
+
+
+@node Kill Files
+@section Kill Files
+@cindex kill files
+
+Gnus still supports those pesky old kill files. In fact, the kill file
+entries can now be expiring, which is something I wrote before Daniel
+Quinlan thought of doing score files, so I've left the code in there.
+
+In short, kill processing is a lot slower (and I do mean @emph{a lot})
+than score processing, so it might be a good idea to rewrite your kill
+files into score files.
+
+Anyway, a kill file is a normal @code{emacs-lisp} file. You can put any
+forms into this file, which means that you can use kill files as some
+sort of primitive hook function to be run on group entry, even though
+that isn't a very good idea.
+
+Normal kill files look like this:
+
+@lisp
+(gnus-kill "From" "Lars Ingebrigtsen")
+(gnus-kill "Subject" "ding")
+(gnus-expunge "X")
+@end lisp
+
+This will mark every article written by me as read, and remove the
+marked articles from the summary buffer. Very useful, you'll agree.
+
+Other programs use a totally different kill file syntax. If Gnus
+encounters what looks like a @code{rn} kill file, it will take a stab at
+interpreting it.
+
+Two summary functions for editing a @sc{gnus} kill file:
+
+@table @kbd
+
+@item M-k
+@kindex M-k (Summary)
+@findex gnus-summary-edit-local-kill
+Edit this group's kill file (@code{gnus-summary-edit-local-kill}).
+
+@item M-K
+@kindex M-K (Summary)
+@findex gnus-summary-edit-global-kill
+Edit the general kill file (@code{gnus-summary-edit-global-kill}).
+@end table
+
+Two group mode functions for editing the kill files:
+
+@table @kbd
+
+@item M-k
+@kindex M-k (Group)
+@findex gnus-group-edit-local-kill
+Edit this group's kill file (@code{gnus-group-edit-local-kill}).
+
+@item M-K
+@kindex M-K (Group)
+@findex gnus-group-edit-global-kill
+Edit the general kill file (@code{gnus-group-edit-global-kill}).
+@end table
+
+Kill file variables:
+
+@table @code
+@item gnus-kill-file-name
+@vindex gnus-kill-file-name
+A kill file for the group @samp{soc.motss} is normally called
+@file{soc.motss.KILL}. The suffix appended to the group name to get
+this file name is detailed by the @code{gnus-kill-file-name} variable.
+The ``global'' kill file (not in the score file sense of ``global'', of
+course) is just called @file{KILL}.
+
+@vindex gnus-kill-save-kill-file
+@item gnus-kill-save-kill-file
+If this variable is non-@code{nil}, Gnus will save the
+kill file after processing, which is necessary if you use expiring
+kills.
+
+@item gnus-apply-kill-hook
+@vindex gnus-apply-kill-hook
+@findex gnus-apply-kill-file-unless-scored
+@findex gnus-apply-kill-file
+A hook called to apply kill files to a group. It is
+@code{(gnus-apply-kill-file)} by default. If you want to ignore the
+kill file if you have a score file for the same group, you can set this
+hook to @code{(gnus-apply-kill-file-unless-scored)}. If you don't want
+kill files to be processed, you should set this variable to @code{nil}.
+
+@item gnus-kill-file-mode-hook
+@vindex gnus-kill-file-mode-hook
+A hook called in kill-file mode buffers.
+
+@end table
+
+
+@node Converting Kill Files
+@section Converting Kill Files
+@cindex kill files
+@cindex converting kill files
+
+If you have loads of old kill files, you may want to convert them into
+score files. If they are ``regular'', you can use
+the @file{gnus-kill-to-score.el} package; if not, you'll have to do it
+by hand.
+
+The kill to score conversion package isn't included in Emacs by default.
+You can fetch it from the contrib directory of the Gnus distribution or
+from
+@uref{http://heim.ifi.uio.no/~larsi/ding-various/gnus-kill-to-score.el}.
+
+If your old kill files are very complex---if they contain more
+non-@code{gnus-kill} forms than not, you'll have to convert them by
+hand. Or just let them be as they are. Gnus will still use them as
+before.
+
+
+@node Advanced Scoring
+@section Advanced Scoring
+
+Scoring on Subjects and From headers is nice enough, but what if you're
+really interested in what a person has to say only when she's talking
+about a particular subject? Or what if you really don't want to
+read what person A has to say when she's following up to person B, but
+want to read what she says when she's following up to person C?
+
+By using advanced scoring rules you may create arbitrarily complex
+scoring patterns.
+
+@menu
+* Advanced Scoring Syntax:: A definition.
+* Advanced Scoring Examples:: What they look like.
+* Advanced Scoring Tips:: Getting the most out of it.
+@end menu
+
+
+@node Advanced Scoring Syntax
+@subsection Advanced Scoring Syntax
+
+Ordinary scoring rules have a string as the first element in the rule.
+Advanced scoring rules have a list as the first element. The second
+element is the score to be applied if the first element evaluated to a
+non-@code{nil} value.
+
+These lists may consist of three logical operators, one redirection
+operator, and various match operators.
+
+Logical operators:
+
+@table @code
+@item &
+@itemx and
+This logical operator will evaluate each of its arguments until it finds
+one that evaluates to @code{false}, and then it'll stop. If all arguments
+evaluate to @code{true} values, then this operator will return
+@code{true}.
+
+@item |
+@itemx or
+This logical operator will evaluate each of its arguments until it finds
+one that evaluates to @code{true}. If no arguments are @code{true},
+then this operator will return @code{false}.
+
+@item !
+@itemx not
+@itemx ¬
+This logical operator only takes a single argument. It returns the
+logical negation of the value of its argument.
+
+@end table
+
+There is an @dfn{indirection operator} that will make its arguments
+apply to the ancestors of the current article being scored. For
+instance, @code{1-} will make score rules apply to the parent of the
+current article. @code{2-} will make score rules apply to the
+grandparent of the current article. Alternatively, you can write
+@code{^^}, where the number of @code{^}s (carets) says how far back into
+the ancestry you want to go.
+
+Finally, we have the match operators. These are the ones that do the
+real work. Match operators are header name strings followed by a match
+and a match type. A typical match operator looks like @samp{("from"
+"Lars Ingebrigtsen" s)}. The header names are the same as when using
+simple scoring, and the match types are also the same.
+
+
+@node Advanced Scoring Examples
+@subsection Advanced Scoring Examples
+
+Please note that the following examples are score file rules. To
+make a complete score file from them, surround them with another pair
+of parentheses.
+
+Let's say you want to increase the score of articles written by Lars
+when he's talking about Gnus:
+
+@example
+@group
+((&
+ ("from" "Lars Ingebrigtsen")
+ ("subject" "Gnus"))
+ 1000)
+@end group
+@end example
+
+Quite simple, huh?
+
+When he writes long articles, he sometimes has something nice to say:
+
+@example
+((&
+ ("from" "Lars Ingebrigtsen")
+ (|
+ ("subject" "Gnus")
+ ("lines" 100 >)))
+ 1000)
+@end example
+
+However, when he responds to things written by Reig Eigil Logge, you
+really don't want to read what he's written:
+
+@example
+((&
+ ("from" "Lars Ingebrigtsen")
+ (1- ("from" "Reig Eigil Logge")))
+ -100000)
+@end example
+
+Everybody that follows up Redmondo when he writes about disappearing
+socks should have their scores raised, but only when they talk about
+white socks. However, when Lars talks about socks, it's usually not
+very interesting:
+
+@example
+((&
+ (1-
+ (&
+ ("from" "redmondo@@.*no" r)
+ ("body" "disappearing.*socks" t)))
+ (! ("from" "Lars Ingebrigtsen"))
+ ("body" "white.*socks"))
+ 1000)
+@end example
+
+Suppose you're reading a high volume group and you're only interested
+in replies. The plan is to score down all articles that don't have
+subject that begin with "Re:", "Fw:" or "Fwd:" and then score up all
+parents of articles that have subjects that begin with reply marks.
+
+@example
+((! ("subject" "re:\\|fwd?:" r))
+ -200)
+((1- ("subject" "re:\\|fwd?:" r))
+ 200)
+@end example
+
+The possibilities are endless.
+
+@node Advanced Scoring Tips
+@subsection Advanced Scoring Tips
+
+The @code{&} and @code{|} logical operators do short-circuit logic.
+That is, they stop processing their arguments when it's clear what the
+result of the operation will be. For instance, if one of the arguments
+of an @code{&} evaluates to @code{false}, there's no point in evaluating
+the rest of the arguments. This means that you should put slow matches
+(@samp{body}, @samp{header}) last and quick matches (@samp{from},
+@samp{subject}) first.
+
+The indirection arguments (@code{1-} and so on) will make their
+arguments work on previous generations of the thread. If you say
+something like:
+
+@example
+...
+(1-
+ (1-
+ ("from" "lars")))
+...
+@end example
+
+Then that means ``score on the from header of the grandparent of the
+current article''. An indirection is quite fast, but it's better to say:
+
+@example
+(1-
+ (&
+ ("from" "Lars")
+ ("subject" "Gnus")))
+@end example
+
+than it is to say:
+
+@example
+(&
+ (1- ("from" "Lars"))
+ (1- ("subject" "Gnus")))
+@end example
+
+
+@node Score Decays
+@section Score Decays
+@cindex score decays
+@cindex decays
+
+You may find that your scores have a tendency to grow without
+bounds, especially if you're using adaptive scoring. If scores get too
+big, they lose all meaning---they simply max out and it's difficult to
+use them in any sensible way.
+
+@vindex gnus-decay-scores
+@findex gnus-decay-score
+@vindex gnus-decay-score-function
+Gnus provides a mechanism for decaying scores to help with this problem.
+When score files are loaded and @code{gnus-decay-scores} is
+non-@code{nil}, Gnus will run the score files through the decaying
+mechanism thereby lowering the scores of all non-permanent score rules.
+If @code{gnus-decay-scores} is a regexp, only score files matching this
+regexp are treated. E.g., you may set it to @samp{\\.ADAPT\\'} if only
+@emph{adaptive} score files should be decayed. The decay itself if
+performed by the @code{gnus-decay-score-function} function, which is
+@code{gnus-decay-score} by default. Here's the definition of that
+function:
+
+@lisp
+(defun gnus-decay-score (score)
+ "Decay SCORE according to `gnus-score-decay-constant'
+and `gnus-score-decay-scale'."
+ (let ((n (- score
+ (* (if (< score 0) -1 1)
+ (min (abs score)
+ (max gnus-score-decay-constant
+ (* (abs score)
+ gnus-score-decay-scale)))))))
+ (if (and (featurep 'xemacs)
+ ;; XEmacs's floor can handle only the floating point
+ ;; number below the half of the maximum integer.
+ (> (abs n) (lsh -1 -2)))
+ (string-to-number
+ (car (split-string (number-to-string n) "\\.")))
+ (floor n))))
+@end lisp
+
+@vindex gnus-score-decay-scale
+@vindex gnus-score-decay-constant
+@code{gnus-score-decay-constant} is 3 by default and
+@code{gnus-score-decay-scale} is 0.05. This should cause the following:
+
+@enumerate
+@item
+Scores between -3 and 3 will be set to 0 when this function is called.
+
+@item
+Scores with magnitudes between 3 and 60 will be shrunk by 3.
+
+@item
+Scores with magnitudes greater than 60 will be shrunk by 5% of the
+score.
+@end enumerate
+
+If you don't like this decay function, write your own. It is called
+with the score to be decayed as its only parameter, and it should return
+the new score, which should be an integer.
+
+Gnus will try to decay scores once a day. If you haven't run Gnus for
+four days, Gnus will decay the scores four times, for instance.
+
+@node Searching
+@chapter Searching
+@cindex searching
+
+FIXME: Add a brief overview of Gnus search capabilities. A brief
+comparison of nnir, nnmairix, contrib/gnus-namazu would be nice
+as well.
+
+This chapter describes tools for searching groups and servers for
+articles matching a query and then retrieving those articles. Gnus
+provides a simpler mechanism for searching through articles in a summary buffer
+to find those matching a pattern. @xref{Searching for Articles}.
+
+@menu
+* nnir:: Searching with various engines.
+* nnmairix:: Searching with Mairix.
+@end menu
+
+@node nnir
+@section nnir
+@cindex nnir
+
+This section describes how to use @code{nnir} to search for articles
+within gnus.
+
+@menu
+* What is nnir?:: What does @code{nnir} do?
+* Basic Usage:: How to perform simple searches.
+* Setting up nnir:: How to set up @code{nnir}.
+@end menu
+
+@node What is nnir?
+@subsection What is nnir?
+
+@code{nnir} is a Gnus interface to a number of tools for searching
+through mail and news repositories. Different backends (like
+@code{nnimap} and @code{nntp}) work with different tools (called
+@dfn{engines} in @code{nnir} lingo), but all use the same basic search
+interface.
+
+The @code{nnimap} and @code{gmane} search engines should work with no
+configuration. Other engines require a local index that needs to be
+created and maintained outside of Gnus.
+
+
+@node Basic Usage
+@subsection Basic Usage
+
+In the group buffer typing @kbd{G G} will search the group on the
+current line by calling @code{gnus-group-make-nnir-group}. This prompts
+for a query string, creates an ephemeral @code{nnir} group containing
+the articles that match this query, and takes you to a summary buffer
+showing these articles. Articles may then be read, moved and deleted
+using the usual commands.
+
+The @code{nnir} group made in this way is an @code{ephemeral} group,
+and some changes are not permanent: aside from reading, moving, and
+deleting, you can't act on the original article. But there is an
+alternative: you can @emph{warp} (i.e., jump) to the original group
+for the article on the current line with @kbd{A W}, aka
+@code{gnus-warp-to-article}. Even better, the function
+@code{gnus-summary-refer-thread}, bound by default in summary buffers
+to @kbd{A T}, will first warp to the original group before it works
+its magic and includes all the articles in the thread. From here you
+can read, move and delete articles, but also copy them, alter article
+marks, whatever. Go nuts.
+
+You say you want to search more than just the group on the current line?
+No problem: just process-mark the groups you want to search. You want
+even more? Calling for an nnir search with the cursor on a topic heading
+will search all the groups under that heading.
+
+Still not enough? OK, in the server buffer
+@code{gnus-group-make-nnir-group} (now bound to @kbd{G}) will search all
+groups from the server on the current line. Too much? Want to ignore
+certain groups when searching, like spam groups? Just customize
+@code{nnir-ignored-newsgroups}.
+
+One more thing: individual search engines may have special search
+features. You can access these special features by giving a prefix-arg
+to @code{gnus-group-make-nnir-group}. If you are searching multiple
+groups with different search engines you will be prompted for the
+special search features for each engine separately.
+
+
+@node Setting up nnir
+@subsection Setting up nnir
+
+To set up nnir you may need to do some prep work. Firstly, you may need
+to configure the search engines you plan to use. Some of them, like
+@code{imap} and @code{gmane}, need no special configuration. Others,
+like @code{namazu} and @code{swish}, require configuration as described
+below. Secondly, you need to associate a search engine with a server or
+a backend.
+
+If you just want to use the @code{imap} engine to search @code{nnimap}
+servers, and the @code{gmane} engine to search @code{gmane} then you
+don't have to do anything. But you might want to read the details of the
+query language anyway.
+
+@menu
+* Associating Engines:: How to associate engines.
+* The imap Engine:: Imap configuration and usage.
+* The gmane Engine:: Gmane configuration and usage.
+* The swish++ Engine:: Swish++ configuration and usage.
+* The swish-e Engine:: Swish-e configuration and usage.
+* The namazu Engine:: Namazu configuration and usage.
+* The notmuch Engine:: Notmuch configuration and usage.
+* The hyrex Engine:: Hyrex configuration and usage.
+* Customizations:: User customizable settings.
+@end menu
+
+@node Associating Engines
+@subsubsection Associating Engines
+
+
+When searching a group, @code{nnir} needs to know which search engine to
+use. You can configure a given server to use a particular engine by
+setting the server variable @code{nnir-search-engine} to the engine
+name. For example to use the @code{namazu} engine to search the server
+named @code{home} you can use
+
+@lisp
+(setq gnus-secondary-select-methods
+ '((nnml "home"
+ (nnimap-address "localhost")
+ (nnir-search-engine namazu))))
+@end lisp
+
+Alternatively you might want to use a particular engine for all servers
+with a given backend. For example, you might want to use the @code{imap}
+engine for all servers using the @code{nnimap} backend. In this case you
+can customize the variable @code{nnir-method-default-engines}. This is
+an alist of pairs of the form @code{(backend . engine)}. By default this
+variable is set to use the @code{imap} engine for all servers using the
+@code{nnimap} backend, and the @code{gmane} backend for @code{nntp}
+servers. (Don't worry, the @code{gmane} search engine won't actually try
+to search non-gmane @code{nntp} servers.) But if you wanted to use
+@code{namazu} for all your servers with an @code{nnimap} backend you
+could change this to
+
+@lisp
+'((nnimap . namazu)
+ (nntp . gmane))
+@end lisp
+
+@node The imap Engine
+@subsubsection The imap Engine
+
+The @code{imap} engine requires no configuration.
+
+Queries using the @code{imap} engine follow a simple query language.
+The search is always case-insensitive and supports the following
+features (inspired by the Google search input language):
+
+@table @samp
+
+@item Boolean query operators
+AND, OR, and NOT are supported, and parentheses can be used to control
+operator precedence, e.g., (emacs OR xemacs) AND linux. Note that
+operators must be written with all capital letters to be
+recognized. Also preceding a term with a @minus{} sign is equivalent
+to NOT term.
+
+@item Automatic AND queries
+If you specify multiple words then they will be treated as an AND
+expression intended to match all components.
+
+@item Phrase searches
+If you wrap your query in double-quotes then it will be treated as a
+literal string.
+
+@end table
+
+By default the whole message will be searched. The query can be limited
+to a specific part of a message by using a prefix-arg. After inputting
+the query this will prompt (with completion) for a message part.
+Choices include ``Whole message'', ``Subject'', ``From'', and
+``To''. Any unrecognized input is interpreted as a header name. For
+example, typing @kbd{Message-ID} in response to this prompt will limit
+the query to the Message-ID header.
+
+Finally selecting ``Imap'' will interpret the query as a raw
+@acronym{IMAP} search query. The format of such queries can be found in
+RFC3501.
+
+If you don't like the default of searching whole messages you can
+customize @code{nnir-imap-default-search-key}. For example to use
+@acronym{IMAP} queries by default
+
+@lisp
+(setq nnir-imap-default-search-key "Imap")
+@end lisp
+
+@node The gmane Engine
+@subsubsection The gmane Engine
+
+The @code{gmane} engine requires no configuration.
+
+Gmane queries follow a simple query language:
+
+@table @samp
+@item Boolean query operators
+AND, OR, NOT (or AND NOT), and XOR are supported, and brackets can be
+used to control operator precedence, e.g., (emacs OR xemacs) AND linux.
+Note that operators must be written with all capital letters to be
+recognized.
+
+@item Required and excluded terms
++ and @minus{} can be used to require or exclude terms, e.g., football
+@minus{}american
+
+@item Unicode handling
+The search engine converts all text to utf-8, so searching should work
+in any language.
+
+@item Stopwords
+Common English words (like 'the' and 'a') are ignored by default. You
+can override this by prefixing such words with a + (e.g., +the) or
+enclosing the word in quotes (e.g., "the").
+
+@end table
+
+The query can be limited to articles by a specific author using a
+prefix-arg. After inputting the query this will prompt for an author
+name (or part of a name) to match.
+
+@node The swish++ Engine
+@subsubsection The swish++ Engine
+
+FIXME: Say something more here.
+
+Documentation for swish++ may be found at the swish++ sourceforge page:
+@uref{http://swishplusplus.sourceforge.net}
+
+@table @code
+
+@item nnir-swish++-program
+The name of the swish++ executable. Defaults to @code{search}
+
+@item nnir-swish++-additional-switches
+A list of strings to be given as additional arguments to
+swish++. @code{nil} by default.
+
+@item nnir-swish++-remove-prefix
+The prefix to remove from each file name returned by swish++ in order
+to get a group name. By default this is @code{$HOME/Mail}.
+
+@end table
+
+@node The swish-e Engine
+@subsubsection The swish-e Engine
+
+FIXME: Say something more here.
+
+Documentation for swish-e may be found at the swish-e homepage
+@uref{http://swish-e.org}
+
+@table @code
+
+@item nnir-swish-e-program
+The name of the swish-e search program. Defaults to @code{swish-e}.
+
+@item nnir-swish-e-additional-switches
+A list of strings to be given as additional arguments to
+swish-e. @code{nil} by default.
+
+@item nnir-swish-e-remove-prefix
+The prefix to remove from each file name returned by swish-e in order
+to get a group name. By default this is @code{$HOME/Mail}.
+
+@end table
+
+@node The namazu Engine
+@subsubsection The namazu Engine
+
+Using the namazu engine requires creating and maintaining index files.
+One directory should contain all the index files, and nnir must be told
+where to find them by setting the @code{nnir-namazu-index-directory}
+variable.
+
+To work correctly the @code{nnir-namazu-remove-prefix} variable must
+also be correct. This is the prefix to remove from each file name
+returned by Namazu in order to get a proper group name (albeit with @samp{/}
+instead of @samp{.}).
+
+For example, suppose that Namazu returns file names such as
+@samp{/home/john/Mail/mail/misc/42}. For this example, use the
+following setting: @code{(setq nnir-namazu-remove-prefix
+"/home/john/Mail/")} Note the trailing slash. Removing this prefix from
+the directory gives @samp{mail/misc/42}. @code{nnir} knows to remove
+the @samp{/42} and to replace @samp{/} with @samp{.} to arrive at the
+correct group name @samp{mail.misc}.
+
+Extra switches may be passed to the namazu search command by setting the
+variable @code{nnir-namazu-additional-switches}. It is particularly
+important not to pass any any switches to namazu that will change the
+output format. Good switches to use include @option{--sort},
+@option{--ascending}, @option{--early} and @option{--late}.
+Refer to the Namazu documentation for further
+information on valid switches.
+
+Mail must first be indexed with the @command{mknmz} program. Read the
+documentation for namazu to create a configuration file. Here is an
+example:
+
+@cartouche
+@example
+ package conf; # Don't remove this line!
+
+ # Paths which will not be indexed. Don't use '^' or '$' anchors.
+ $EXCLUDE_PATH = "spam|sent";
+
+ # Header fields which should be searchable. case-insensitive
+ $REMAIN_HEADER = "from|date|message-id|subject";
+
+ # Searchable fields. case-insensitive
+ $SEARCH_FIELD = "from|date|message-id|subject";
+
+ # The max length of a word.
+ $WORD_LENG_MAX = 128;
+
+ # The max length of a field.
+ $MAX_FIELD_LENGTH = 256;
+@end example
+@end cartouche
+
+For this example, mail is stored in the directories @samp{~/Mail/mail/},
+@samp{~/Mail/lists/} and @samp{~/Mail/archive/}, so to index them go to
+the index directory set in @code{nnir-namazu-index-directory} and issue
+the following command:
+
+@example
+mknmz --mailnews ~/Mail/archive/ ~/Mail/mail/ ~/Mail/lists/
+@end example
+
+For maximum searching efficiency you might want to have a cron job run
+this command periodically, say every four hours.
+
+
+@node The notmuch Engine
+@subsubsection The notmuch Engine
+
+@table @code
+@item nnir-notmuch-program
+The name of the notmuch search executable. Defaults to
+@samp{notmuch}.
+
+@item nnir-notmuch-additional-switches
+A list of strings, to be given as additional arguments to notmuch.
+
+@item nnir-notmuch-remove-prefix
+The prefix to remove from each file name returned by notmuch in order
+to get a group name (albeit with @samp{/} instead of @samp{.}). This
+is a regular expression.
+
+@end table
+
+
+@node The hyrex Engine
+@subsubsection The hyrex Engine
+This engine is obsolete.
+
+@node Customizations
+@subsubsection Customizations
+
+@table @code
+
+@item nnir-method-default-engines
+Alist of pairs of server backends and search engines. The default
+associations are
+@example
+(nnimap . imap)
+(nntp . gmane)
+@end example
+
+@item nnir-ignored-newsgroups
+A regexp to match newsgroups in the active file that should be skipped
+when searching all groups on a server.
+
+@item nnir-summary-line-format
+The format specification to be used for lines in an nnir summary buffer.
+All the items from @code{gnus-summary-line-format} are available, along with
+three items unique to nnir summary buffers:
+
+@example
+%Z Search retrieval score value (integer)
+%G Article original full group name (string)
+%g Article original short group name (string)
+@end example
+
+If @code{nil} (the default) this will use @code{gnus-summary-line-format}.
+
+@item nnir-retrieve-headers-override-function
+If non-@code{nil}, a function that retrieves article headers rather than using
+the gnus built-in function. This function takes an article list and
+group as arguments and populates the @code{nntp-server-buffer} with the
+retrieved headers. It should then return either 'nov or 'headers
+indicating the retrieved header format. Failure to retrieve headers
+should return @code{nil}.
+
+If this variable is @code{nil}, or if the provided function returns
+@code{nil} for a search result, @code{gnus-retrieve-headers} will be
+called instead."
+
+
+@end table
+
+
+@node nnmairix
+@section nnmairix
+
+@cindex mairix
+@cindex nnmairix
+This paragraph describes how to set up mairix and the back end
+@code{nnmairix} for indexing and searching your mail from within
+Gnus. Additionally, you can create permanent ``smart'' groups which are
+bound to mairix searches and are automatically updated.
+
+@menu
+* About mairix:: About the mairix mail search engine
+* nnmairix requirements:: What you will need for using nnmairix
+* What nnmairix does:: What does nnmairix actually do?
+* Setting up mairix:: Set up your mairix installation
+* Configuring nnmairix:: Set up the nnmairix back end
+* nnmairix keyboard shortcuts:: List of available keyboard shortcuts
+* Propagating marks:: How to propagate marks from nnmairix groups
+* nnmairix tips and tricks:: Some tips, tricks and examples
+* nnmairix caveats:: Some more stuff you might want to know
+@end menu
+
+@c FIXME: The markup in this section might need improvement.
+@c E.g., adding @samp, @var, @file, @command, etc.
+@c Cf. (info "(texinfo)Indicating")
+
+@node About mairix
+@subsection About mairix
+
+Mairix is a tool for indexing and searching words in locally stored
+mail. It was written by Richard Curnow and is licensed under the
+GPL@. Mairix comes with most popular GNU/Linux distributions, but it also
+runs under Windows (with cygwin), Mac OS X and Solaris. The homepage can
+be found at
+@uref{http://www.rpcurnow.force9.co.uk/mairix/index.html}
+
+Though mairix might not be as flexible as other search tools like
+swish++ or namazu, which you can use via the @code{nnir} back end, it
+has the prime advantage of being incredibly fast. On current systems, it
+can easily search through headers and message bodies of thousands and
+thousands of mails in well under a second. Building the database
+necessary for searching might take a minute or two, but only has to be
+done once fully. Afterwards, the updates are done incrementally and
+therefore are really fast, too. Additionally, mairix is very easy to set
+up.
+
+For maximum speed though, mairix should be used with mails stored in
+@code{Maildir} or @code{MH} format (this includes the @code{nnml} back
+end), although it also works with mbox. Mairix presents the search
+results by populating a @emph{virtual} maildir/MH folder with symlinks
+which point to the ``real'' message files (if mbox is used, copies are
+made). Since mairix already presents search results in such a virtual
+mail folder, it is very well suited for using it as an external program
+for creating @emph{smart} mail folders, which represent certain mail
+searches.
+
+@node nnmairix requirements
+@subsection nnmairix requirements
+
+Mairix searches local mail---that means, mairix absolutely must have
+direct access to your mail folders. If your mail resides on another
+server (e.g., an @acronym{IMAP} server) and you happen to have shell
+access, @code{nnmairix} supports running mairix remotely, e.g., via ssh.
+
+Additionally, @code{nnmairix} only supports the following Gnus back
+ends: @code{nnml}, @code{nnmaildir}, and @code{nnimap}. You must use
+one of these back ends for using @code{nnmairix}. Other back ends, like
+@code{nnmbox}, @code{nnfolder} or @code{nnmh}, won't work.
+
+If you absolutely must use mbox and still want to use @code{nnmairix},
+you can set up a local @acronym{IMAP} server, which you then access via
+@code{nnimap}. This is a rather massive setup for accessing some mbox
+files, so just change to MH or Maildir already... However, if you're
+really, really passionate about using mbox, you might want to look into
+the package @file{mairix.el}, which comes with Emacs 23.
+
+@node What nnmairix does
+@subsection What nnmairix does
+
+The back end @code{nnmairix} enables you to call mairix from within Gnus,
+either to query mairix with a search term or to update the
+database. While visiting a message in the summary buffer, you can use
+several pre-defined shortcuts for calling mairix, e.g., to quickly
+search for all mails from the sender of the current message or to
+display the whole thread associated with the message, even if the
+mails are in different folders.
+
+Additionally, you can create permanent @code{nnmairix} groups which are bound
+to certain mairix searches. This way, you can easily create a group
+containing mails from a certain sender, with a certain subject line or
+even for one specific thread based on the Message-ID@. If you check for
+new mail in these folders (e.g., by pressing @kbd{g} or @kbd{M-g}), they
+automatically update themselves by calling mairix.
+
+You might ask why you need @code{nnmairix} at all, since mairix already
+creates the group, populates it with links to the mails so that you can
+then access it with Gnus, right? Well, this @emph{might} work, but often
+does not---at least not without problems. Most probably you will get
+strange article counts, and sometimes you might see mails which Gnus
+claims have already been canceled and are inaccessible. This is due to
+the fact that Gnus isn't really amused when things are happening behind
+its back. Another problem can be the mail back end itself, e.g., if you
+use mairix with an @acronym{IMAP} server (I had Dovecot complaining
+about corrupt index files when mairix changed the contents of the search
+group). Using @code{nnmairix} should circumvent these problems.
+
+@code{nnmairix} is not really a mail back end---it's actually more like
+a wrapper, sitting between a ``real'' mail back end where mairix stores
+the searches and the Gnus front end. You can choose between three
+different mail back ends for the mairix folders: @code{nnml},
+@code{nnmaildir} or @code{nnimap}. @code{nnmairix} will call the mairix
+binary so that the search results are stored in folders named
+@code{zz_mairix-<NAME>-<NUMBER>} on this mail back end, but it will
+present these folders in the Gnus front end only with @code{<NAME>}.
+You can use an existing mail back end where you already store your mail,
+but if you're uncomfortable with @code{nnmairix} creating new mail
+groups alongside your other mail, you can also create, e.g., a new
+@code{nnmaildir} or @code{nnml} server exclusively for mairix, but then
+make sure those servers do not accidentally receive your new mail
+(@pxref{nnmairix caveats}). A special case exists if you want to use
+mairix remotely on an IMAP server with @code{nnimap}---here the mairix
+folders and your other mail must be on the same @code{nnimap} back end.
+
+@node Setting up mairix
+@subsection Setting up mairix
+
+First: create a backup of your mail folders (@pxref{nnmairix caveats}).
+
+Setting up mairix is easy: simply create a @file{.mairixrc} file with
+(at least) the following entries:
+
+@example
+# Your Maildir/MH base folder
+base=~/Maildir
+@end example
+
+This is the base folder for your mails. All the following directories
+are relative to this base folder. If you want to use @code{nnmairix}
+with @code{nnimap}, this base directory has to point to the mail
+directory where the @acronym{IMAP} server stores the mail folders!
+
+@example
+maildir= ... your maildir folders which should be indexed ...
+mh= ... your nnml/mh folders which should be indexed ...
+mbox = ... your mbox files which should be indexed ...
+@end example
+
+This specifies all your mail folders and mbox files (relative to the
+base directory!) you want to index with mairix. Note that the
+@code{nnml} back end saves mails in MH format, so you have to put those
+directories in the @code{mh} line. See the example at the end of this
+section and mairixrc's man-page for further details.
+
+@example
+omit=zz_mairix-*
+@end example
+
+@vindex nnmairix-group-prefix
+This should make sure that you don't accidentally index the mairix
+search results. You can change the prefix of these folders with the
+variable @code{nnmairix-group-prefix}.
+
+@example
+mformat= ... 'maildir' or 'mh' ...
+database= ... location of database file ...
+@end example
+
+The @code{format} setting specifies the output format for the mairix
+search folder. Set this to @code{mh} if you want to access search results
+with @code{nnml}. Otherwise choose @code{maildir}.
+
+To summarize, here is my shortened @file{.mairixrc} file as an example:
+
+@example
+base=~/Maildir
+maildir=.personal:.work:.logcheck:.sent
+mh=../Mail/nnml/*...
+mbox=../mboxmail/mailarchive_year*
+mformat=maildir
+omit=zz_mairix-*
+database=~/.mairixdatabase
+@end example
+
+In this case, the base directory is @file{~/Maildir}, where all my Maildir
+folders are stored. As you can see, the folders are separated by
+colons. If you wonder why every folder begins with a dot: this is
+because I use Dovecot as @acronym{IMAP} server, which again uses
+@code{Maildir++} folders. For testing nnmairix, I also have some
+@code{nnml} mail, which is saved in @file{~/Mail/nnml}. Since this has
+to be specified relative to the @code{base} directory, the @code{../Mail}
+notation is needed. Note that the line ends in @code{*...}, which means
+to recursively scan all files under this directory. Without the three
+dots, the wildcard @code{*} will not work recursively. I also have some
+old mbox files with archived mail lying around in @file{~/mboxmail}.
+The other lines should be obvious.
+
+See the man page for @code{mairixrc} for details and further options,
+especially regarding wildcard usage, which may be a little different
+than you are used to.
+
+Now simply call @code{mairix} to create the index for the first time.
+Note that this may take a few minutes, but every following index will do
+the updates incrementally and hence is very fast.
+
+@node Configuring nnmairix
+@subsection Configuring nnmairix
+
+In group mode, type @kbd{G b c}
+(@code{nnmairix-create-server-and-default-group}). This will ask you for all
+necessary information and create a @code{nnmairix} server as a foreign
+server. You will have to specify the following:
+
+@itemize @bullet
+
+@item
+The @strong{name} of the @code{nnmairix} server---choose whatever you
+want.
+
+@item
+The name of the @strong{back end server} where mairix should store its
+searches. This must be a full server name, like @code{nnml:mymail}.
+Just hit @kbd{TAB} to see the available servers. Currently, servers
+which are accessed through @code{nnmaildir}, @code{nnimap} and
+@code{nnml} are supported. As explained above, for locally stored
+mails, this can be an existing server where you store your mails.
+However, you can also create, e.g., a new @code{nnmaildir} or @code{nnml}
+server exclusively for @code{nnmairix} in your secondary select methods
+(@pxref{Finding the News}). If you use a secondary @code{nnml} server
+just for mairix, make sure that you explicitly set the server variable
+@code{nnml-get-new-mail} to @code{nil}, or you might lose mail
+(@pxref{nnmairix caveats}). If you want to use mairix remotely on an
+@acronym{IMAP} server, you have to choose the corresponding
+@code{nnimap} server here.
+
+@item
+@vindex nnmairix-mairix-search-options
+The @strong{command} to call the mairix binary. This will usually just
+be @code{mairix}, but you can also choose something like @code{ssh
+SERVER mairix} if you want to call mairix remotely, e.g., on your
+@acronym{IMAP} server. If you want to add some default options to
+mairix, you could do this here, but better use the variable
+@code{nnmairix-mairix-search-options} instead.
+
+@item
+The name of the @strong{default search group}. This will be the group
+where all temporary mairix searches are stored, i.e., all searches which
+are not bound to permanent @code{nnmairix} groups. Choose whatever you
+like.
+
+@item
+If the mail back end is @code{nnimap} or @code{nnmaildir}, you will be
+asked if you work with @strong{Maildir++}, i.e., with hidden maildir
+folders (=beginning with a dot). For example, you have to answer
+@samp{yes} here if you work with the Dovecot @acronym{IMAP}
+server. Otherwise, you should answer @samp{no} here.
+
+@end itemize
+
+@node nnmairix keyboard shortcuts
+@subsection nnmairix keyboard shortcuts
+
+In group mode:
+
+@table @kbd
+
+@item G b c
+@kindex G b c (Group)
+@findex nnmairix-create-server-and-default-group
+Creates @code{nnmairix} server and default search group for this server
+(@code{nnmairix-create-server-and-default-group}). You should have done
+this by now (@pxref{Configuring nnmairix}).
+
+@item G b s
+@kindex G b s (Group)
+@findex nnmairix-search
+Prompts for query which is then sent to the mairix binary. Search
+results are put into the default search group which is automatically
+displayed (@code{nnmairix-search}).
+
+@item G b m
+@kindex G b m (Group)
+@findex nnmairix-widget-search
+Allows you to create a mairix search or a permanent group more
+comfortably using graphical widgets, similar to a customization
+group. Just try it to see how it works (@code{nnmairix-widget-search}).
+
+@item G b i
+@kindex G b i (Group)
+@findex nnmairix-search-interactive
+Another command for creating a mairix query more comfortably, but uses
+only the minibuffer (@code{nnmairix-search-interactive}).
+
+@item G b g
+@kindex G b g (Group)
+@findex nnmairix-create-search-group
+Creates a permanent group which is associated with a search query
+(@code{nnmairix-create-search-group}). The @code{nnmairix} back end
+automatically calls mairix when you update this group with @kbd{g} or
+@kbd{M-g}.
+
+@item G b q
+@kindex G b q (Group)
+@findex nnmairix-group-change-query-this-group
+Changes the search query for the @code{nnmairix} group under cursor
+(@code{nnmairix-group-change-query-this-group}).
+
+@item G b t
+@kindex G b t (Group)
+@findex nnmairix-group-toggle-threads-this-group
+Toggles the 'threads' parameter for the @code{nnmairix} group under cursor,
+i.e., if you want see the whole threads of the found messages
+(@code{nnmairix-group-toggle-threads-this-group}).
+
+@item G b u
+@kindex G b u (Group)
+@findex nnmairix-update-database
+@vindex nnmairix-mairix-update-options
+Calls mairix binary for updating the database
+(@code{nnmairix-update-database}). The default parameters are @code{-F}
+and @code{-Q} for making this as fast as possible (see variable
+@code{nnmairix-mairix-update-options} for defining these default
+options).
+
+@item G b r
+@kindex G b r (Group)
+@findex nnmairix-group-toggle-readmarks-this-group
+Keep articles in this @code{nnmairix} group always read or unread, or leave the
+marks unchanged (@code{nnmairix-group-toggle-readmarks-this-group}).
+
+@item G b d
+@kindex G b d (Group)
+@findex nnmairix-group-delete-recreate-this-group
+Recreate @code{nnmairix} group on the ``real'' mail back end
+(@code{nnmairix-group-delete-recreate-this-group}). You can do this if
+you always get wrong article counts with a @code{nnmairix} group.
+
+@item G b a
+@kindex G b a (Group)
+@findex nnmairix-group-toggle-allowfast-this-group
+Toggles the @code{allow-fast} parameters for group under cursor
+(@code{nnmairix-group-toggle-allowfast-this-group}). The default
+behavior of @code{nnmairix} is to do a mairix search every time you
+update or enter the group. With the @code{allow-fast} parameter set,
+mairix will only be called when you explicitly update the group, but not
+upon entering. This makes entering the group faster, but it may also
+lead to dangling symlinks if something changed between updating and
+entering the group which is not yet in the mairix database.
+
+@item G b p
+@kindex G b p (Group)
+@findex nnmairix-group-toggle-propmarks-this-group
+Toggle marks propagation for this group
+(@code{nnmairix-group-toggle-propmarks-this-group}). (@pxref{Propagating
+marks}).
+
+@item G b o
+@kindex G b o (Group)
+@findex nnmairix-propagate-marks
+Manually propagate marks (@code{nnmairix-propagate-marks}); needed only when
+@code{nnmairix-propagate-marks-upon-close} is set to @code{nil}.
+
+@end table
+
+In summary mode:
+
+@table @kbd
+
+@item $ m
+@kindex $ m (Summary)
+@findex nnmairix-widget-search-from-this-article
+Allows you to create a mairix query or group based on the current
+message using graphical widgets (same as @code{nnmairix-widget-search})
+(@code{nnmairix-widget-search-from-this-article}).
+
+@item $ g
+@kindex $ g (Summary)
+@findex nnmairix-create-search-group-from-message
+Interactively creates a new search group with query based on the current
+message, but uses the minibuffer instead of graphical widgets
+(@code{nnmairix-create-search-group-from-message}).
+
+@item $ t
+@kindex $ t (Summary)
+@findex nnmairix-search-thread-this-article
+Searches thread for the current article
+(@code{nnmairix-search-thread-this-article}). This is effectively a
+shortcut for calling @code{nnmairix-search} with @samp{m:msgid} of the
+current article and enabled threads.
+
+@item $ f
+@kindex $ f (Summary)
+@findex nnmairix-search-from-this-article
+Searches all messages from sender of the current article
+(@code{nnmairix-search-from-this-article}). This is a shortcut for
+calling @code{nnmairix-search} with @samp{f:From}.
+
+@item $ o
+@kindex $ o (Summary)
+@findex nnmairix-goto-original-article
+(Only in @code{nnmairix} groups!) Tries determine the group this article
+originally came from and displays the article in this group, so that,
+e.g., replying to this article the correct posting styles/group
+parameters are applied (@code{nnmairix-goto-original-article}). This
+function will use the registry if available, but can also parse the
+article file name as a fallback method.
+
+@item $ u
+@kindex $ u (Summary)
+@findex nnmairix-remove-tick-mark-original-article
+Remove possibly existing tick mark from original article
+(@code{nnmairix-remove-tick-mark-original-article}). (@pxref{nnmairix
+tips and tricks}).
+
+@end table
+
+@node Propagating marks
+@subsection Propagating marks
+
+First of: you really need a patched mairix binary for using the marks
+propagation feature efficiently. Otherwise, you would have to update
+the mairix database all the time. You can get the patch at
+
+@uref{http://www.randomsample.de/mairix-maildir-patch.tar}
+
+You need the mairix v0.21 source code for this patch; everything else
+is explained in the accompanied readme file. If you don't want to use
+marks propagation, you don't have to apply these patches, but they also
+fix some annoyances regarding changing maildir flags, so it might still
+be useful to you.
+
+With the patched mairix binary, you can use @code{nnmairix} as an
+alternative to mail splitting (@pxref{Fancy Mail Splitting}). For
+example, instead of splitting all mails from @samp{david@@foobar.com}
+into a group, you can simply create a search group with the query
+@samp{f:david@@foobar.com}. This is actually what ``smart folders'' are
+all about: simply put everything in one mail folder and dynamically
+create searches instead of splitting. This is more flexible, since you
+can dynamically change your folders any time you want to. This also
+implies that you will usually read your mails in the @code{nnmairix}
+groups instead of your ``real'' mail groups.
+
+There is one problem, though: say you got a new mail from
+@samp{david@@foobar.com}; it will now show up in two groups, the
+``real'' group (your INBOX, for example) and in the @code{nnmairix}
+search group (provided you have updated the mairix database). Now you
+enter the @code{nnmairix} group and read the mail. The mail will be
+marked as read, but only in the @code{nnmairix} group---in the ``real''
+mail group it will be still shown as unread.
+
+You could now catch up the mail group (@pxref{Group Data}), but this is
+tedious and error prone, since you may overlook mails you don't have
+created @code{nnmairix} groups for. Of course, you could first use
+@code{nnmairix-goto-original-article} (@pxref{nnmairix keyboard
+shortcuts}) and then read the mail in the original group, but that's
+even more cumbersome.
+
+Clearly, the easiest way would be if marks could somehow be
+automatically set for the original article. This is exactly what
+@emph{marks propagation} is about.
+
+Marks propagation is inactive by default. You can activate it for a
+certain @code{nnmairix} group with
+@code{nnmairix-group-toggle-propmarks-this-group} (bound to @kbd{G b
+p}). This function will warn you if you try to use it with your default
+search group; the reason is that the default search group is used for
+temporary searches, and it's easy to accidentally propagate marks from
+this group. However, you can ignore this warning if you really want to.
+
+With marks propagation enabled, all the marks you set in a @code{nnmairix}
+group should now be propagated to the original article. For example,
+you can now tick an article (by default with @kbd{!}) and this mark should
+magically be set for the original article, too.
+
+A few more remarks which you may or may not want to know:
+
+@vindex nnmairix-propagate-marks-upon-close
+Marks will not be set immediately, but only upon closing a group. This
+not only makes marks propagation faster, it also avoids problems with
+dangling symlinks when dealing with maildir files (since changing flags
+will change the file name). You can also control when to propagate marks
+via @code{nnmairix-propagate-marks-upon-close} (see the doc-string for
+details).
+
+Obviously, @code{nnmairix} will have to look up the original group for every
+article you want to set marks for. If available, @code{nnmairix} will first
+use the registry for determining the original group. The registry is very
+fast, hence you should really, really enable the registry when using
+marks propagation. If you don't have to worry about RAM and disc space,
+set @code{gnus-registry-max-entries} to a large enough value; to be on
+the safe side, choose roughly the amount of mails you index with mairix.
+
+@vindex nnmairix-only-use-registry
+If you don't want to use the registry or the registry hasn't seen the
+original article yet, @code{nnmairix} will use an additional mairix
+search for determining the file name of the article. This, of course, is
+way slower than the registry---if you set hundreds or even thousands of
+marks this way, it might take some time. You can avoid this situation by
+setting @code{nnmairix-only-use-registry} to @code{t}.
+
+Maybe you also want to propagate marks the other way round, i.e., if you
+tick an article in a "real" mail group, you'd like to have the same
+article in a @code{nnmairix} group ticked, too. For several good
+reasons, this can only be done efficiently if you use maildir. To
+immediately contradict myself, let me mention that it WON'T work with
+@code{nnmaildir}, since @code{nnmaildir} stores the marks externally and
+not in the file name. Therefore, propagating marks to @code{nnmairix}
+groups will usually only work if you use an IMAP server which uses
+maildir as its file format.
+
+@vindex nnmairix-propagate-marks-to-nnmairix-groups
+If you work with this setup, just set
+@code{nnmairix-propagate-marks-to-nnmairix-groups} to @code{t} and see what
+happens. If you don't like what you see, just set it to @code{nil} again.
+One problem might be that you get a wrong number of unread articles; this
+usually happens when you delete or expire articles in the original
+groups. When this happens, you can recreate the @code{nnmairix} group on
+the back end using @kbd{G b d}.
+
+@node nnmairix tips and tricks
+@subsection nnmairix tips and tricks
+
+@itemize
+@item
+Checking Mail
+
+@findex nnmairix-update-groups
+I put all my important mail groups at group level 1. The mairix groups
+have group level 5, so they do not get checked at start up (@pxref{Group
+Levels}).
+
+I use the following to check for mails:
+
+@lisp
+(defun my-check-mail-mairix-update (level)
+ (interactive "P")
+ ;; if no prefix given, set level=1
+ (gnus-group-get-new-news (or level 1))
+ (nnmairix-update-groups "mairixsearch" t t)
+ (gnus-group-list-groups))
+
+(define-key gnus-group-mode-map "g" 'my-check-mail-mairix-update)
+@end lisp
+
+Instead of @samp{"mairixsearch"} use the name of your @code{nnmairix}
+server. See the doc string for @code{nnmairix-update-groups} for
+details.
+
+@item
+Example: search group for ticked articles
+
+For example, you can create a group for all ticked articles, where the
+articles always stay unread:
+
+Hit @kbd{G b g}, enter group name (e.g., @samp{important}), use
+@samp{F:f} as query and do not include threads.
+
+Now activate marks propagation for this group by using @kbd{G b p}. Then
+activate the always-unread feature by using @kbd{G b r} twice.
+
+So far so good---but how do you remove the tick marks in the @code{nnmairix}
+group? There are two options: You may simply use
+@code{nnmairix-remove-tick-mark-original-article} (bound to @kbd{$ u}) to remove
+tick marks from the original article. The other possibility is to set
+@code{nnmairix-propagate-marks-to-nnmairix-groups} to @code{t}, but see the above
+comments about this option. If it works for you, the tick marks should
+also exist in the @code{nnmairix} group and you can remove them as usual,
+e.g., by marking an article as read.
+
+When you have removed a tick mark from the original article, this
+article should vanish from the @code{nnmairix} group after you have updated the
+mairix database and updated the group. Fortunately, there is a function
+for doing exactly that: @code{nnmairix-update-groups}. See the previous code
+snippet and the doc string for details.
+
+@item
+Dealing with auto-subscription of mail groups
+
+As described before, all @code{nnmairix} groups are in fact stored on
+the mail back end in the form @samp{zz_mairix-<NAME>-<NUMBER>}. You can
+see them when you enter the back end server in the server buffer. You
+should not subscribe these groups! Unfortunately, these groups will
+usually get @emph{auto-subscribed} when you use @code{nnmaildir} or
+@code{nnml}, i.e., you will suddenly see groups of the form
+@samp{zz_mairix*} pop up in your group buffer. If this happens to you,
+simply kill these groups with C-k. For avoiding this, turn off
+auto-subscription completely by setting the variable
+@code{gnus-auto-subscribed-groups} to @code{nil} (@pxref{Filtering New
+Groups}), or if you like to keep this feature use the following kludge
+for turning it off for all groups beginning with @samp{zz_}:
+
+@lisp
+(setq gnus-auto-subscribed-groups
+ "^\\(nnml\\|nnfolder\\|nnmbox\\|nnmh\\|nnbabyl\\|nnmaildir\\).*:\\([^z]\\|z$\\|\\z[^z]\\|zz$\\|zz[^_]\\|zz_$\\).*")
+@end lisp
+
+@end itemize
+
+@node nnmairix caveats
+@subsection nnmairix caveats
+
+@itemize
+@item
+You can create a secondary @code{nnml} server just for nnmairix, but then
+you have to explicitly set the corresponding server variable
+@code{nnml-get-new-mail} to @code{nil}. Otherwise, new mail might get
+put into this secondary server (and would never show up again). Here's
+an example server definition:
+
+@lisp
+(nnml "mairix" (nnml-directory "mairix") (nnml-get-new-mail nil))
+@end lisp
+
+(The @code{nnmaildir} back end also has a server variable
+@code{get-new-mail}, but its default value is @code{nil}, so you don't
+have to explicitly set it if you use a @code{nnmaildir} server just for
+mairix.)
+
+@item
+If you use the Gnus registry: don't use the registry with
+@code{nnmairix} groups (put them in
+@code{gnus-registry-unfollowed-groups}; this is the default). Be
+@emph{extra careful} if you use
+@code{gnus-registry-split-fancy-with-parent}; mails which are split
+into @code{nnmairix} groups are usually gone for good as soon as you
+check the group for new mail (yes, it has happened to me...).
+
+@item
+Therefore: @emph{Never ever} put ``real'' mails into @code{nnmairix}
+groups (you shouldn't be able to, anyway).
+
+@item
+If you use the Gnus agent (@pxref{Gnus Unplugged}): don't agentize
+@code{nnmairix} groups (though I have no idea what happens if you do).
+
+@item
+mairix does only support us-ascii characters.
+
+@item
+@code{nnmairix} uses a rather brute force method to force Gnus to
+completely reread the group on the mail back end after mairix was
+called---it simply deletes and re-creates the group on the mail
+back end. So far, this has worked for me without any problems, and I
+don't see how @code{nnmairix} could delete other mail groups than its
+own, but anyway: you really should have a backup of your mail
+folders.
+
+@item
+All necessary information is stored in the group parameters
+(@pxref{Group Parameters}). This has the advantage that no active file
+is needed, but also implies that when you kill a @code{nnmairix} group,
+it is gone for good.
+
+@item
+@findex nnmairix-purge-old-groups
+If you create and kill a lot of @code{nnmairix} groups, the
+``zz_mairix-*'' groups will accumulate on the mail back end server. To
+delete old groups which are no longer needed, call
+@code{nnmairix-purge-old-groups}. Note that this assumes that you don't
+save any ``real'' mail in folders of the form
+@code{zz_mairix-<NAME>-<NUMBER>}. You can change the prefix of
+@code{nnmairix} groups by changing the variable
+@code{nnmairix-group-prefix}.
+
+@item
+The following only applies if you @emph{don't} use the mentioned patch
+for mairix (@pxref{Propagating marks}):
+
+A problem can occur when using @code{nnmairix} with maildir folders and
+comes with the fact that maildir stores mail flags like @samp{Seen} or
+@samp{Replied} by appending chars @samp{S} and @samp{R} to the message
+file name, respectively. This implies that currently you would have to
+update the mairix database not only when new mail arrives, but also when
+mail flags are changing. The same applies to new mails which are indexed
+while they are still in the @samp{new} folder but then get moved to
+@samp{cur} when Gnus has seen the mail. If you don't update the database
+after this has happened, a mairix query can lead to symlinks pointing to
+non-existing files. In Gnus, these messages will usually appear with
+``(none)'' entries in the header and can't be accessed. If this happens
+to you, using @kbd{G b u} and updating the group will usually fix this.
+
+@end itemize
+
+@iftex
+@iflatex
+@chapter Message
+@include message.texi
+@chapter Emacs MIME
+@include emacs-mime.texi
+@chapter Sieve
+@include sieve.texi
+@chapter EasyPG
+@include epa.texi
+@chapter SASL
+@include sasl.texi
+@end iflatex
+@end iftex
+
+@node Various
+@chapter Various
+
+@menu
+* Process/Prefix:: A convention used by many treatment commands.
+* Interactive:: Making Gnus ask you many questions.
+* Symbolic Prefixes:: How to supply some Gnus functions with options.
+* Formatting Variables:: You can specify what buffers should look like.
+* Window Layout:: Configuring the Gnus buffer windows.
+* Faces and Fonts:: How to change how faces look.
+* Mode Lines:: Displaying information in the mode lines.
+* Highlighting and Menus:: Making buffers look all nice and cozy.
+* Daemons:: Gnus can do things behind your back.
+* Undo:: Some actions can be undone.
+* Predicate Specifiers:: Specifying predicates.
+* Moderation:: What to do if you're a moderator.
+* Fetching a Group:: Starting Gnus just to read a group.
+* Image Enhancements:: Modern versions of Emacs/XEmacs can display images.
+* Fuzzy Matching:: What's the big fuzz?
+* Thwarting Email Spam:: Simple ways to avoid unsolicited commercial email.
+* Spam Package:: A package for filtering and processing spam.
+* The Gnus Registry:: A package for tracking messages by Message-ID.
+* Other modes:: Interaction with other modes.
+* Various Various:: Things that are really various.
+@end menu
+
+
+@node Process/Prefix
+@section Process/Prefix
+@cindex process/prefix convention
+
+Many functions, among them functions for moving, decoding and saving
+articles, use what is known as the @dfn{Process/Prefix convention}.
+
+This is a method for figuring out what articles the user wants the
+command to be performed on.
+
+It goes like this:
+
+If the numeric prefix is N, perform the operation on the next N
+articles, starting with the current one. If the numeric prefix is
+negative, perform the operation on the previous N articles, starting
+with the current one.
+
+@vindex transient-mark-mode
+If @code{transient-mark-mode} in non-@code{nil} and the region is
+active, all articles in the region will be worked upon.
+
+If there is no numeric prefix, but some articles are marked with the
+process mark, perform the operation on the articles marked with
+the process mark.
+
+If there is neither a numeric prefix nor any articles marked with the
+process mark, just perform the operation on the current article.
+
+Quite simple, really, but it needs to be made clear so that surprises
+are avoided.
+
+Commands that react to the process mark will push the current list of
+process marked articles onto a stack and will then clear all process
+marked articles. You can restore the previous configuration with the
+@kbd{M P y} command (@pxref{Setting Process Marks}).
+
+@vindex gnus-summary-goto-unread
+One thing that seems to shock & horrify lots of people is that, for
+instance, @kbd{3 d} does exactly the same as @kbd{d} @kbd{d} @kbd{d}.
+Since each @kbd{d} (which marks the current article as read) by default
+goes to the next unread article after marking, this means that @kbd{3 d}
+will mark the next three unread articles as read, no matter what the
+summary buffer looks like. Set @code{gnus-summary-goto-unread} to
+@code{nil} for a more straightforward action.
+
+Many commands do not use the process/prefix convention. All commands
+that do explicitly say so in this manual. To apply the process/prefix
+convention to commands that do not use it, you can use the @kbd{M-&}
+command. For instance, to mark all the articles in the group as
+expirable, you could say @kbd{M P b M-& E}.
+
+
+@node Interactive
+@section Interactive
+@cindex interaction
+
+@table @code
+
+@item gnus-novice-user
+@vindex gnus-novice-user
+If this variable is non-@code{nil}, you are either a newcomer to the
+World of Usenet, or you are very cautious, which is a nice thing to be,
+really. You will be given questions of the type ``Are you sure you want
+to do this?'' before doing anything dangerous. This is @code{t} by
+default.
+
+@item gnus-expert-user
+@vindex gnus-expert-user
+If this variable is non-@code{nil}, you will seldom be asked any
+questions by Gnus. It will simply assume you know what you're doing,
+no matter how strange. For example, quitting Gnus, exiting a group
+without an update, catching up with a group, deleting expired
+articles, and replying by mail to a news message will not require
+confirmation.
+
+@item gnus-interactive-catchup
+@vindex gnus-interactive-catchup
+Require confirmation before catching up a group if non-@code{nil}. It
+is @code{t} by default.
+
+@item gnus-interactive-exit
+@vindex gnus-interactive-exit
+If non-@code{nil}, require a confirmation when exiting Gnus. If
+@code{quiet}, update any active summary buffers automatically without
+querying. The default value is @code{t}.
+@end table
+
+
+@node Symbolic Prefixes
+@section Symbolic Prefixes
+@cindex symbolic prefixes
+
+Quite a lot of Emacs commands react to the (numeric) prefix. For
+instance, @kbd{C-u 4 C-f} moves point four characters forward, and
+@kbd{C-u 9 0 0 I s s p} adds a permanent @code{Subject} substring score
+rule of 900 to the current article.
+
+This is all nice and well, but what if you want to give a command some
+additional information? Well, what most commands do is interpret the
+``raw'' prefix in some special way. @kbd{C-u 0 C-x C-s} means that one
+doesn't want a backup file to be created when saving the current buffer,
+for instance. But what if you want to save without making a backup
+file, and you want Emacs to flash lights and play a nice tune at the
+same time? You can't, and you're probably perfectly happy that way.
+
+@kindex M-i (Summary)
+@findex gnus-symbolic-argument
+I'm not, so I've added a second prefix---the @dfn{symbolic prefix}. The
+prefix key is @kbd{M-i} (@code{gnus-symbolic-argument}), and the next
+character typed in is the value. You can stack as many @kbd{M-i}
+prefixes as you want. @kbd{M-i a C-M-u} means ``feed the @kbd{C-M-u}
+command the symbolic prefix @code{a}''. @kbd{M-i a M-i b C-M-u} means
+``feed the @kbd{C-M-u} command the symbolic prefixes @code{a} and
+@code{b}''. You get the drift.
+
+Typing in symbolic prefixes to commands that don't accept them doesn't
+hurt, but it doesn't do any good either. Currently not many Gnus
+functions make use of the symbolic prefix.
+
+If you're interested in how Gnus implements this, @pxref{Extended
+Interactive}.
+
+
+@node Formatting Variables
+@section Formatting Variables
+@cindex formatting variables
+
+Throughout this manual you've probably noticed lots of variables called
+things like @code{gnus-group-line-format} and
+@code{gnus-summary-mode-line-format}. These control how Gnus is to
+output lines in the various buffers. There's quite a lot of them.
+Fortunately, they all use the same syntax, so there's not that much to
+be annoyed by.
+
+Here's an example format spec (from the group buffer): @samp{%M%S%5y:
+%(%g%)\n}. We see that it is indeed extremely ugly, and that there are
+lots of percentages everywhere.
+
+@menu
+* Formatting Basics:: A formatting variable is basically a format string.
+* Mode Line Formatting:: Some rules about mode line formatting variables.
+* Advanced Formatting:: Modifying output in various ways.
+* User-Defined Specs:: Having Gnus call your own functions.
+* Formatting Fonts:: Making the formatting look colorful and nice.
+* Positioning Point:: Moving point to a position after an operation.
+* Tabulation:: Tabulating your output.
+* Wide Characters:: Dealing with wide characters.
+@end menu
+
+Currently Gnus uses the following formatting variables:
+@code{gnus-group-line-format}, @code{gnus-summary-line-format},
+@code{gnus-server-line-format}, @code{gnus-topic-line-format},
+@code{gnus-group-mode-line-format},
+@code{gnus-summary-mode-line-format},
+@code{gnus-article-mode-line-format},
+@code{gnus-server-mode-line-format}, and
+@code{gnus-summary-pick-line-format}.
+
+All these format variables can also be arbitrary elisp forms. In that
+case, they will be @code{eval}ed to insert the required lines.
+
+@kindex M-x gnus-update-format
+@findex gnus-update-format
+Gnus includes a command to help you while creating your own format
+specs. @kbd{M-x gnus-update-format} will @code{eval} the current form,
+update the spec in question and pop you to a buffer where you can
+examine the resulting Lisp code to be run to generate the line.
+
+
+
+@node Formatting Basics
+@subsection Formatting Basics
+
+Each @samp{%} element will be replaced by some string or other when the
+buffer in question is generated. @samp{%5y} means ``insert the @samp{y}
+spec, and pad with spaces to get a 5-character field''.
+
+As with normal C and Emacs Lisp formatting strings, the numerical
+modifier between the @samp{%} and the formatting type character will
+@dfn{pad} the output so that it is always at least that long.
+@samp{%5y} will make the field always (at least) five characters wide by
+padding with spaces to the left. If you say @samp{%-5y}, it will pad to
+the right instead.
+
+You may also wish to limit the length of the field to protect against
+particularly wide values. For that you can say @samp{%4,6y}, which
+means that the field will never be more than 6 characters wide and never
+less than 4 characters wide.
+
+Also Gnus supports some extended format specifications, such as
+@samp{%&user-date;}.
+
+
+@node Mode Line Formatting
+@subsection Mode Line Formatting
+
+Mode line formatting variables (e.g.,
+@code{gnus-summary-mode-line-format}) follow the same rules as other,
+buffer line oriented formatting variables (@pxref{Formatting Basics})
+with the following two differences:
+
+@enumerate
+
+@item
+There must be no newline (@samp{\n}) at the end.
+
+@item
+The special @samp{%%b} spec can be used to display the buffer name.
+Well, it's no spec at all, really---@samp{%%} is just a way to quote
+@samp{%} to allow it to pass through the formatting machinery unmangled,
+so that Emacs receives @samp{%b}, which is something the Emacs mode line
+display interprets to mean ``show the buffer name''. For a full list of
+mode line specs Emacs understands, see the documentation of the
+@code{mode-line-format} variable.
+
+@end enumerate
+
+
+@node Advanced Formatting
+@subsection Advanced Formatting
+
+It is frequently useful to post-process the fields in some way.
+Padding, limiting, cutting off parts and suppressing certain values can
+be achieved by using @dfn{tilde modifiers}. A typical tilde spec might
+look like @samp{%~(cut 3)~(ignore "0")y}.
+
+These are the valid modifiers:
+
+@table @code
+@item pad
+@itemx pad-left
+Pad the field to the left with spaces until it reaches the required
+length.
+
+@item pad-right
+Pad the field to the right with spaces until it reaches the required
+length.
+
+@item max
+@itemx max-left
+Cut off characters from the left until it reaches the specified length.
+
+@item max-right
+Cut off characters from the right until it reaches the specified
+length.
+
+@item cut
+@itemx cut-left
+Cut off the specified number of characters from the left.
+
+@item cut-right
+Cut off the specified number of characters from the right.
+
+@item ignore
+Return an empty string if the field is equal to the specified value.
+
+@item form
+Use the specified form as the field value when the @samp{@@} spec is
+used.
+
+Here's an example:
+
+@lisp
+"~(form (current-time-string))@@"
+@end lisp
+
+@end table
+
+Let's take an example. The @samp{%o} spec in the summary mode lines
+will return a date in compact ISO8601 format---@samp{19960809T230410}.
+This is quite a mouthful, so we want to shave off the century number and
+the time, leaving us with a six-character date. That would be
+@samp{%~(cut-left 2)~(max-right 6)~(pad 6)o}. (Cutting is done before
+maxing, and we need the padding to ensure that the date is never less
+than 6 characters to make it look nice in columns.)
+
+Ignoring is done first; then cutting; then maxing; and then as the very
+last operation, padding.
+
+
+@node User-Defined Specs
+@subsection User-Defined Specs
+
+All the specs allow for inserting user defined specifiers---@samp{u}.
+The next character in the format string should be a letter. Gnus
+will call the function @code{gnus-user-format-function-}@samp{X}, where
+@samp{X} is the letter following @samp{%u}. The function will be passed
+a single parameter---what the parameter means depends on what buffer
+it's being called from. The function should return a string, which will
+be inserted into the buffer just like information from any other
+specifier. This function may also be called with dummy values, so it
+should protect against that.
+
+Also Gnus supports extended user-defined specs, such as @samp{%u&foo;}.
+Gnus will call the function @code{gnus-user-format-function-}@samp{foo}.
+
+You can also use tilde modifiers (@pxref{Advanced Formatting} to achieve
+much the same without defining new functions. Here's an example:
+@samp{%~(form (count-lines (point-min) (point)))@@}. The form
+given here will be evaluated to yield the current line number, and then
+inserted.
+
+
+@node Formatting Fonts
+@subsection Formatting Fonts
+
+@cindex %(, %)
+@vindex gnus-mouse-face
+There are specs for highlighting, and these are shared by all the format
+variables. Text inside the @samp{%(} and @samp{%)} specifiers will get
+the special @code{mouse-face} property set, which means that it will be
+highlighted (with @code{gnus-mouse-face}) when you put the mouse pointer
+over it.
+
+@cindex %@{, %@}
+@vindex gnus-face-0
+Text inside the @samp{%@{} and @samp{%@}} specifiers will have their
+normal faces set using @code{gnus-face-0}, which is @code{bold} by
+default. If you say @samp{%1@{}, you'll get @code{gnus-face-1} instead,
+and so on. Create as many faces as you wish. The same goes for the
+@code{mouse-face} specs---you can say @samp{%3(hello%)} to have
+@samp{hello} mouse-highlighted with @code{gnus-mouse-face-3}.
+
+@cindex %<<, %>>, guillemets
+@c @cindex %<<, %>>, %«, %», guillemets
+@vindex gnus-balloon-face-0
+Text inside the @samp{%<<} and @samp{%>>} specifiers will get the
+special @code{balloon-help} property set to
+@code{gnus-balloon-face-0}. If you say @samp{%1<<}, you'll get
+@code{gnus-balloon-face-1} and so on. The @code{gnus-balloon-face-*}
+variables should be either strings or symbols naming functions that
+return a string. When the mouse passes over text with this property
+set, a balloon window will appear and display the string. Please
+refer to @ref{Tooltips, ,Tooltips, emacs, The Emacs Manual},
+(in Emacs) or the doc string of @code{balloon-help-mode} (in
+XEmacs) for more information on this. (For technical reasons, the
+guillemets have been approximated as @samp{<<} and @samp{>>} in this
+paragraph.)
+
+Here's an alternative recipe for the group buffer:
+
+@lisp
+;; @r{Create three face types.}
+(setq gnus-face-1 'bold)
+(setq gnus-face-3 'italic)
+
+;; @r{We want the article count to be in}
+;; @r{a bold and green face. So we create}
+;; @r{a new face called @code{my-green-bold}.}
+(copy-face 'bold 'my-green-bold)
+;; @r{Set the color.}
+(set-face-foreground 'my-green-bold "ForestGreen")
+(setq gnus-face-2 'my-green-bold)
+
+;; @r{Set the new & fancy format.}
+(setq gnus-group-line-format
+ "%M%S%3@{%5y%@}%2[:%] %(%1@{%g%@}%)\n")
+@end lisp
+
+I'm sure you'll be able to use this scheme to create totally unreadable
+and extremely vulgar displays. Have fun!
+
+Note that the @samp{%(} specs (and friends) do not make any sense on the
+mode-line variables.
+
+@node Positioning Point
+@subsection Positioning Point
+
+Gnus usually moves point to a pre-defined place on each line in most
+buffers. By default, point move to the first colon character on the
+line. You can customize this behavior in three different ways.
+
+You can move the colon character to somewhere else on the line.
+
+@findex gnus-goto-colon
+You can redefine the function that moves the point to the colon. The
+function is called @code{gnus-goto-colon}.
+
+But perhaps the most convenient way to deal with this, if you don't want
+to have a colon in your line, is to use the @samp{%*} specifier. If you
+put a @samp{%*} somewhere in your format line definition, Gnus will
+place point there.
+
+
+@node Tabulation
+@subsection Tabulation
+
+You can usually line up your displays by padding and cutting your
+strings. However, when combining various strings of different size, it
+can often be more convenient to just output the strings, and then worry
+about lining up the following text afterwards.
+
+To do that, Gnus supplies tabulator specs---@samp{%=}. There are two
+different types---@dfn{hard tabulators} and @dfn{soft tabulators}.
+
+@samp{%50=} will insert space characters to pad the line up to column
+50. If the text is already past column 50, nothing will be inserted.
+This is the soft tabulator.
+
+@samp{%-50=} will insert space characters to pad the line up to column
+50. If the text is already past column 50, the excess text past column
+50 will be removed. This is the hard tabulator.
+
+
+@node Wide Characters
+@subsection Wide Characters
+
+Fixed width fonts in most countries have characters of the same width.
+Some countries, however, use Latin characters mixed with wider
+characters---most notable East Asian countries.
+
+The problem is that when formatting, Gnus assumes that if a string is 10
+characters wide, it'll be 10 Latin characters wide on the screen. In
+these countries, that's not true.
+
+@vindex gnus-use-correct-string-widths
+To help fix this, you can set @code{gnus-use-correct-string-widths} to
+@code{t}. This makes buffer generation slower, but the results will be
+prettier. The default value under XEmacs is @code{t} but @code{nil}
+for Emacs.
+
+
+@node Window Layout
+@section Window Layout
+@cindex window layout
+
+No, there's nothing here about X, so be quiet.
+
+@vindex gnus-use-full-window
+If @code{gnus-use-full-window} non-@code{nil}, Gnus will delete all
+other windows and occupy the entire Emacs screen by itself. It is
+@code{t} by default.
+
+Setting this variable to @code{nil} kinda works, but there are
+glitches. Use at your own peril.
+
+@vindex gnus-buffer-configuration
+@code{gnus-buffer-configuration} describes how much space each Gnus
+buffer should be given. Here's an excerpt of this variable:
+
+@lisp
+((group (vertical 1.0 (group 1.0 point)))
+ (article (vertical 1.0 (summary 0.25 point)
+ (article 1.0))))
+@end lisp
+
+This is an alist. The @dfn{key} is a symbol that names some action or
+other. For instance, when displaying the group buffer, the window
+configuration function will use @code{group} as the key. A full list of
+possible names is listed below.
+
+The @dfn{value} (i.e., the @dfn{split}) says how much space each buffer
+should occupy. To take the @code{article} split as an example:
+
+@lisp
+(article (vertical 1.0 (summary 0.25 point)
+ (article 1.0)))
+@end lisp
+
+This @dfn{split} says that the summary buffer should occupy 25% of upper
+half of the screen, and that it is placed over the article buffer. As
+you may have noticed, 100% + 25% is actually 125% (yup, I saw y'all
+reaching for that calculator there). However, the special number
+@code{1.0} is used to signal that this buffer should soak up all the
+rest of the space available after the rest of the buffers have taken
+whatever they need. There should be only one buffer with the @code{1.0}
+size spec per split.
+
+Point will be put in the buffer that has the optional third element
+@code{point}. In a @code{frame} split, the last subsplit having a leaf
+split where the tag @code{frame-focus} is a member (i.e., is the third or
+fourth element in the list, depending on whether the @code{point} tag is
+present) gets focus.
+
+Here's a more complicated example:
+
+@lisp
+(article (vertical 1.0 (group 4)
+ (summary 0.25 point)
+ (article 1.0)))
+@end lisp
+
+If the size spec is an integer instead of a floating point number,
+then that number will be used to say how many lines a buffer should
+occupy, not a percentage.
+
+If the @dfn{split} looks like something that can be @code{eval}ed (to be
+precise---if the @code{car} of the split is a function or a subr), this
+split will be @code{eval}ed. If the result is non-@code{nil}, it will
+be used as a split.
+
+Not complicated enough for you? Well, try this on for size:
+
+@lisp
+(article (horizontal 1.0
+ (vertical 0.5
+ (group 1.0))
+ (vertical 1.0
+ (summary 0.25 point)
+ (article 1.0))))
+@end lisp
+
+Whoops. Two buffers with the mystery 100% tag. And what's that
+@code{horizontal} thingie?
+
+If the first element in one of the split is @code{horizontal}, Gnus will
+split the window horizontally, giving you two windows side-by-side.
+Inside each of these strips you may carry on all you like in the normal
+fashion. The number following @code{horizontal} says what percentage of
+the screen is to be given to this strip.
+
+For each split, there @emph{must} be one element that has the 100% tag.
+The splitting is never accurate, and this buffer will eat any leftover
+lines from the splits.
+
+To be slightly more formal, here's a definition of what a valid split
+may look like:
+
+@example
+@group
+split = frame | horizontal | vertical | buffer | form
+frame = "(frame " size *split ")"
+horizontal = "(horizontal " size *split ")"
+vertical = "(vertical " size *split ")"
+buffer = "(" buf-name " " size *[ "point" ] *[ "frame-focus"] ")"
+size = number | frame-params
+buf-name = group | article | summary ...
+@end group
+@end example
+
+The limitations are that the @code{frame} split can only appear as the
+top-level split. @var{form} should be an Emacs Lisp form that should
+return a valid split. We see that each split is fully recursive, and
+may contain any number of @code{vertical} and @code{horizontal} splits.
+
+@vindex gnus-window-min-width
+@vindex gnus-window-min-height
+@cindex window height
+@cindex window width
+Finding the right sizes can be a bit complicated. No window may be less
+than @code{gnus-window-min-height} (default 1) characters high, and all
+windows must be at least @code{gnus-window-min-width} (default 1)
+characters wide. Gnus will try to enforce this before applying the
+splits. If you want to use the normal Emacs window width/height limit,
+you can just set these two variables to @code{nil}.
+
+If you're not familiar with Emacs terminology, @code{horizontal} and
+@code{vertical} splits may work the opposite way of what you'd expect.
+Windows inside a @code{horizontal} split are shown side-by-side, and
+windows within a @code{vertical} split are shown above each other.
+
+@findex gnus-configure-frame
+If you want to experiment with window placement, a good tip is to call
+@code{gnus-configure-frame} directly with a split. This is the function
+that does all the real work when splitting buffers. Below is a pretty
+nonsensical configuration with 5 windows; two for the group buffer and
+three for the article buffer. (I said it was nonsensical.) If you
+@code{eval} the statement below, you can get an idea of how that would
+look straight away, without going through the normal Gnus channels.
+Play with it until you're satisfied, and then use
+@code{gnus-add-configuration} to add your new creation to the buffer
+configuration list.
+
+@lisp
+(gnus-configure-frame
+ '(horizontal 1.0
+ (vertical 10
+ (group 1.0)
+ (article 0.3 point))
+ (vertical 1.0
+ (article 1.0)
+ (horizontal 4
+ (group 1.0)
+ (article 10)))))
+@end lisp
+
+You might want to have several frames as well. No prob---just use the
+@code{frame} split:
+
+@lisp
+(gnus-configure-frame
+ '(frame 1.0
+ (vertical 1.0
+ (summary 0.25 point frame-focus)
+ (article 1.0))
+ (vertical ((height . 5) (width . 15)
+ (user-position . t)
+ (left . -1) (top . 1))
+ (picon 1.0))))
+
+@end lisp
+
+This split will result in the familiar summary/article window
+configuration in the first (or ``main'') frame, while a small additional
+frame will be created where picons will be shown. As you can see,
+instead of the normal @code{1.0} top-level spec, each additional split
+should have a frame parameter alist as the size spec.
+@xref{Frame Parameters, , Frame Parameters, elisp, The GNU Emacs Lisp
+Reference Manual}. Under XEmacs, a frame property list will be
+accepted, too---for instance, @code{(height 5 width 15 left -1 top 1)}
+is such a plist.
+The list of all possible keys for @code{gnus-buffer-configuration} can
+be found in its default value.
+
+Note that the @code{message} key is used for both
+@code{gnus-group-mail} and @code{gnus-summary-mail-other-window}. If
+it is desirable to distinguish between the two, something like this
+might be used:
+
+@lisp
+(message (horizontal 1.0
+ (vertical 1.0 (message 1.0 point))
+ (vertical 0.24
+ (if (buffer-live-p gnus-summary-buffer)
+ '(summary 0.5))
+ (group 1.0))))
+@end lisp
+
+One common desire for a multiple frame split is to have a separate frame
+for composing mail and news while leaving the original frame intact. To
+accomplish that, something like the following can be done:
+
+@lisp
+(message
+ (frame 1.0
+ (if (not (buffer-live-p gnus-summary-buffer))
+ (car (cdr (assoc 'group gnus-buffer-configuration)))
+ (car (cdr (assoc 'summary gnus-buffer-configuration))))
+ (vertical ((user-position . t) (top . 1) (left . 1)
+ (name . "Message"))
+ (message 1.0 point))))
+@end lisp
+
+@findex gnus-add-configuration
+Since the @code{gnus-buffer-configuration} variable is so long and
+complicated, there's a function you can use to ease changing the config
+of a single setting: @code{gnus-add-configuration}. If, for instance,
+you want to change the @code{article} setting, you could say:
+
+@lisp
+(gnus-add-configuration
+ '(article (vertical 1.0
+ (group 4)
+ (summary .25 point)
+ (article 1.0))))
+@end lisp
+
+You'd typically stick these @code{gnus-add-configuration} calls in your
+@file{~/.gnus.el} file or in some startup hook---they should be run after
+Gnus has been loaded.
+
+@vindex gnus-always-force-window-configuration
+If all windows mentioned in the configuration are already visible, Gnus
+won't change the window configuration. If you always want to force the
+``right'' window configuration, you can set
+@code{gnus-always-force-window-configuration} to non-@code{nil}.
+
+If you're using tree displays (@pxref{Tree Display}), and the tree
+window is displayed vertically next to another window, you may also want
+to fiddle with @code{gnus-tree-minimize-window} to avoid having the
+windows resized.
+
+@subsection Window Configuration Names
+
+Here's a list of most of the currently known window configurations,
+and when they're used:
+
+@table @code
+@item group
+The group buffer.
+
+@item summary
+Entering a group and showing only the summary.
+
+@item article
+Selecting an article.
+
+@item server
+The server buffer.
+
+@item browse
+Browsing groups from the server buffer.
+
+@item message
+Composing a (new) message.
+
+@item only-article
+Showing only the article buffer.
+
+@item edit-article
+Editing an article.
+
+@item edit-form
+Editing group parameters and the like.
+
+@item edit-score
+Editing a server definition.
+
+@item post
+Composing a news message.
+
+@item reply
+Replying or following up an article without yanking the text.
+
+@item forward
+Forwarding a message.
+
+@item reply-yank
+Replying or following up an article with yanking the text.
+
+@item mail-bound
+Bouncing a message.
+
+@item pipe
+Sending an article to an external process.
+
+@item bug
+Sending a bug report.
+
+@item score-trace
+Displaying the score trace.
+
+@item score-words
+Displaying the score words.
+
+@item split-trace
+Displaying the split trace.
+
+@item compose-bounce
+Composing a bounce message.
+
+@item mml-preview
+Previewing a @acronym{MIME} part.
+
+@end table
+
+
+@subsection Example Window Configurations
+
+@itemize @bullet
+@item
+Narrow left hand side occupied by group buffer. Right hand side split
+between summary buffer (top one-sixth) and article buffer (bottom).
+
+@ifinfo
+@example
++---+---------+
+| G | Summary |
+| r +---------+
+| o | |
+| u | Article |
+| p | |
++---+---------+
+@end example
+@end ifinfo
+
+@lisp
+(gnus-add-configuration
+ '(article
+ (horizontal 1.0
+ (vertical 25 (group 1.0))
+ (vertical 1.0
+ (summary 0.16 point)
+ (article 1.0)))))
+
+(gnus-add-configuration
+ '(summary
+ (horizontal 1.0
+ (vertical 25 (group 1.0))
+ (vertical 1.0 (summary 1.0 point)))))
+@end lisp
+
+@end itemize
+
+
+@node Faces and Fonts
+@section Faces and Fonts
+@cindex faces
+@cindex fonts
+@cindex colors
+
+Fiddling with fonts and faces used to be very difficult, but these days
+it is very simple. You simply say @kbd{M-x customize-face}, pick out
+the face you want to alter, and alter it via the standard Customize
+interface.
+
+
+@node Mode Lines
+@section Mode Lines
+@cindex mode lines
+
+@vindex gnus-updated-mode-lines
+@code{gnus-updated-mode-lines} says what buffers should keep their mode
+lines updated. It is a list of symbols. Supported symbols include
+@code{group}, @code{article}, @code{summary}, @code{server},
+@code{browse}, and @code{tree}. If the corresponding symbol is present,
+Gnus will keep that mode line updated with information that may be
+pertinent. If this variable is @code{nil}, screen refresh may be
+quicker.
+
+@cindex display-time
+
+@vindex gnus-mode-non-string-length
+By default, Gnus displays information on the current article in the mode
+lines of the summary and article buffers. The information Gnus wishes
+to display (e.g., the subject of the article) is often longer than the
+mode lines, and therefore have to be cut off at some point. The
+@code{gnus-mode-non-string-length} variable says how long the other
+elements on the line is (i.e., the non-info part). If you put
+additional elements on the mode line (e.g., a clock), you should modify
+this variable:
+
+@c Hook written by Francesco Potortì <pot@cnuce.cnr.it>
+@lisp
+(add-hook 'display-time-hook
+ (lambda () (setq gnus-mode-non-string-length
+ (+ 21
+ (if line-number-mode 5 0)
+ (if column-number-mode 4 0)
+ (length display-time-string)))))
+@end lisp
+
+If this variable is @code{nil} (which is the default), the mode line
+strings won't be chopped off, and they won't be padded either. Note
+that the default is unlikely to be desirable, as even the percentage
+complete in the buffer may be crowded off the mode line; the user should
+configure this variable appropriately for her configuration.
+
+
+@node Highlighting and Menus
+@section Highlighting and Menus
+@cindex visual
+@cindex highlighting
+@cindex menus
+
+@vindex gnus-visual
+The @code{gnus-visual} variable controls most of the Gnus-prettifying
+aspects. If @code{nil}, Gnus won't attempt to create menus or use fancy
+colors or fonts. This will also inhibit loading the @file{gnus-vis.el}
+file.
+
+This variable can be a list of visual properties that are enabled. The
+following elements are valid, and are all included by default:
+
+@table @code
+@item group-highlight
+Do highlights in the group buffer.
+@item summary-highlight
+Do highlights in the summary buffer.
+@item article-highlight
+Do highlights in the article buffer.
+@item highlight
+Turn on highlighting in all buffers.
+@item group-menu
+Create menus in the group buffer.
+@item summary-menu
+Create menus in the summary buffers.
+@item article-menu
+Create menus in the article buffer.
+@item browse-menu
+Create menus in the browse buffer.
+@item server-menu
+Create menus in the server buffer.
+@item score-menu
+Create menus in the score buffers.
+@item menu
+Create menus in all buffers.
+@end table
+
+So if you only want highlighting in the article buffer and menus in all
+buffers, you could say something like:
+
+@lisp
+(setq gnus-visual '(article-highlight menu))
+@end lisp
+
+If you want highlighting only and no menus whatsoever, you'd say:
+
+@lisp
+(setq gnus-visual '(highlight))
+@end lisp
+
+If @code{gnus-visual} is @code{t}, highlighting and menus will be used
+in all Gnus buffers.
+
+Other general variables that influence the look of all buffers include:
+
+@table @code
+@item gnus-mouse-face
+@vindex gnus-mouse-face
+This is the face (i.e., font) used for mouse highlighting in Gnus. No
+mouse highlights will be done if @code{gnus-visual} is @code{nil}.
+
+@end table
+
+There are hooks associated with the creation of all the different menus:
+
+@table @code
+
+@item gnus-article-menu-hook
+@vindex gnus-article-menu-hook
+Hook called after creating the article mode menu.
+
+@item gnus-group-menu-hook
+@vindex gnus-group-menu-hook
+Hook called after creating the group mode menu.
+
+@item gnus-summary-menu-hook
+@vindex gnus-summary-menu-hook
+Hook called after creating the summary mode menu.
+
+@item gnus-server-menu-hook
+@vindex gnus-server-menu-hook
+Hook called after creating the server mode menu.
+
+@item gnus-browse-menu-hook
+@vindex gnus-browse-menu-hook
+Hook called after creating the browse mode menu.
+
+@item gnus-score-menu-hook
+@vindex gnus-score-menu-hook
+Hook called after creating the score mode menu.
+
+@end table
+
+
+@node Daemons
+@section Daemons
+@cindex demons
+@cindex daemons
+
+Gnus, being larger than any program ever written (allegedly), does lots
+of strange stuff that you may wish to have done while you're not
+present. For instance, you may want it to check for new mail once in a
+while. Or you may want it to close down all connections to all servers
+when you leave Emacs idle. And stuff like that.
+
+Gnus will let you do stuff like that by defining various
+@dfn{handlers}. Each handler consists of three elements: A
+@var{function}, a @var{time}, and an @var{idle} parameter.
+
+Here's an example of a handler that closes connections when Emacs has
+been idle for thirty minutes:
+
+@lisp
+(gnus-demon-close-connections nil 30)
+@end lisp
+
+Here's a handler that scans for @acronym{PGP} headers every hour when
+Emacs is idle:
+
+@lisp
+(gnus-demon-scan-pgp 60 t)
+@end lisp
+
+This @var{time} parameter and that @var{idle} parameter work together
+in a strange, but wonderful fashion. Basically, if @var{idle} is
+@code{nil}, then the function will be called every @var{time} minutes.
+
+If @var{idle} is @code{t}, then the function will be called after
+@var{time} minutes only if Emacs is idle. So if Emacs is never idle,
+the function will never be called. But once Emacs goes idle, the
+function will be called every @var{time} minutes.
+
+If @var{idle} is a number and @var{time} is a number, the function will
+be called every @var{time} minutes only when Emacs has been idle for
+@var{idle} minutes.
+
+If @var{idle} is a number and @var{time} is @code{nil}, the function
+will be called once every time Emacs has been idle for @var{idle}
+minutes.
+
+And if @var{time} is a string, it should look like @samp{07:31}, and
+the function will then be called once every day somewhere near that
+time. Modified by the @var{idle} parameter, of course.
+
+@vindex gnus-demon-timestep
+(When I say ``minute'' here, I really mean @code{gnus-demon-timestep}
+seconds. This is 60 by default. If you change that variable,
+all the timings in the handlers will be affected.)
+
+So, if you want to add a handler, you could put something like this in
+your @file{~/.gnus.el} file:
+
+@findex gnus-demon-add-handler
+@lisp
+(gnus-demon-add-handler 'gnus-demon-close-connections 30 t)
+@end lisp
+
+@findex gnus-demon-add-scanmail
+@findex gnus-demon-add-rescan
+@findex gnus-demon-add-scan-timestamps
+@findex gnus-demon-add-disconnection
+Some ready-made functions to do this have been created:
+@code{gnus-demon-add-disconnection},
+@code{gnus-demon-add-nntp-close-connection},
+@code{gnus-demon-add-scan-timestamps}, @code{gnus-demon-add-rescan}, and
+@code{gnus-demon-add-scanmail}. Just put those functions in your
+@file{~/.gnus.el} if you want those abilities.
+
+@findex gnus-demon-init
+@findex gnus-demon-cancel
+@vindex gnus-demon-handlers
+If you add handlers to @code{gnus-demon-handlers} directly, you should
+run @code{gnus-demon-init} to make the changes take hold. To cancel all
+daemons, you can use the @code{gnus-demon-cancel} function.
+
+Note that adding daemons can be pretty naughty if you over do it. Adding
+functions that scan all news and mail from all servers every two seconds
+is a sure-fire way of getting booted off any respectable system. So
+behave.
+
+
+@node Undo
+@section Undo
+@cindex undo
+
+It is very useful to be able to undo actions one has done. In normal
+Emacs buffers, it's easy enough---you just push the @code{undo} button.
+In Gnus buffers, however, it isn't that simple.
+
+The things Gnus displays in its buffer is of no value whatsoever to
+Gnus---it's all just data designed to look nice to the user.
+Killing a group in the group buffer with @kbd{C-k} makes the line
+disappear, but that's just a side-effect of the real action---the
+removal of the group in question from the internal Gnus structures.
+Undoing something like that can't be done by the normal Emacs
+@code{undo} function.
+
+Gnus tries to remedy this somewhat by keeping track of what the user
+does and coming up with actions that would reverse the actions the user
+takes. When the user then presses the @code{undo} key, Gnus will run
+the code to reverse the previous action, or the previous actions.
+However, not all actions are easily reversible, so Gnus currently offers
+a few key functions to be undoable. These include killing groups,
+yanking groups, and changing the list of read articles of groups.
+That's it, really. More functions may be added in the future, but each
+added function means an increase in data to be stored, so Gnus will
+never be totally undoable.
+
+@findex gnus-undo-mode
+@vindex gnus-use-undo
+@findex gnus-undo
+The undoability is provided by the @code{gnus-undo-mode} minor mode. It
+is used if @code{gnus-use-undo} is non-@code{nil}, which is the
+default. The @kbd{C-M-_} key performs the @code{gnus-undo}
+command, which should feel kinda like the normal Emacs @code{undo}
+command.
+
+
+@node Predicate Specifiers
+@section Predicate Specifiers
+@cindex predicate specifiers
+
+Some Gnus variables are @dfn{predicate specifiers}. This is a special
+form that allows flexible specification of predicates without having
+to type all that much.
+
+These specifiers are lists consisting of functions, symbols and lists.
+
+Here's an example:
+
+@lisp
+(or gnus-article-unseen-p
+ gnus-article-unread-p)
+@end lisp
+
+The available symbols are @code{or}, @code{and} and @code{not}. The
+functions all take one parameter.
+
+@findex gnus-make-predicate
+Internally, Gnus calls @code{gnus-make-predicate} on these specifiers
+to create a function that can be called. This input parameter to this
+function will be passed along to all the functions in the predicate
+specifier.
+
+
+@node Moderation
+@section Moderation
+@cindex moderation
+
+If you are a moderator, you can use the @file{gnus-mdrtn.el} package.
+It is not included in the standard Gnus package. Write a mail to
+@samp{larsi@@gnus.org} and state what group you moderate, and you'll
+get a copy.
+
+The moderation package is implemented as a minor mode for summary
+buffers. Put
+
+@lisp
+(add-hook 'gnus-summary-mode-hook 'gnus-moderate)
+@end lisp
+
+in your @file{~/.gnus.el} file.
+
+If you are the moderator of @samp{rec.zoofle}, this is how it's
+supposed to work:
+
+@enumerate
+@item
+You split your incoming mail by matching on
+@samp{Newsgroups:.*rec.zoofle}, which will put all the to-be-posted
+articles in some mail group---for instance, @samp{nnml:rec.zoofle}.
+
+@item
+You enter that group once in a while and post articles using the @kbd{e}
+(edit-and-post) or @kbd{s} (just send unedited) commands.
+
+@item
+If, while reading the @samp{rec.zoofle} newsgroup, you happen upon some
+articles that weren't approved by you, you can cancel them with the
+@kbd{c} command.
+@end enumerate
+
+To use moderation mode in these two groups, say:
+
+@lisp
+(setq gnus-moderated-list
+ "^nnml:rec.zoofle$\\|^rec.zoofle$")
+@end lisp
+
+
+@node Fetching a Group
+@section Fetching a Group
+@cindex fetching a group
+
+@findex gnus-fetch-group
+It is sometimes convenient to be able to just say ``I want to read this
+group and I don't care whether Gnus has been started or not''. This is
+perhaps more useful for people who write code than for users, but the
+command @code{gnus-fetch-group} provides this functionality in any case.
+It takes the group name as a parameter.
+
+
+@node Image Enhancements
+@section Image Enhancements
+
+XEmacs, as well as Emacs 21@footnote{Emacs 21 on MS Windows doesn't
+support images, Emacs 22 does.} and up, are able to display pictures and
+stuff, so Gnus has taken advantage of that.
+
+@menu
+* X-Face:: Display a funky, teensy black-and-white image.
+* Face:: Display a funkier, teensier colored image.
+* Smileys:: Show all those happy faces the way they were meant to be shown.
+* Picons:: How to display pictures of what you're reading.
+* Gravatars:: Display the avatar of people you read.
+* XVarious:: Other XEmacsy Gnusey variables.
+@end menu
+
+
+@node X-Face
+@subsection X-Face
+@cindex x-face
+
+@code{X-Face} headers describe a 48x48 pixel black-and-white (1 bit
+depth) image that's supposed to represent the author of the message.
+It seems to be supported by an ever-growing number of mail and news
+readers.
+
+@cindex x-face
+@findex gnus-article-display-x-face
+@vindex gnus-article-x-face-command
+@vindex gnus-article-x-face-too-ugly
+@iftex
+@iflatex
+\include{xface}
+@end iflatex
+@end iftex
+@c @anchor{X-Face}
+
+Viewing an @code{X-Face} header either requires an Emacs that has
+@samp{compface} support (which most XEmacs versions have), or that you
+have suitable conversion or display programs installed. If your Emacs
+has image support the default action is to display the face before the
+@code{From} header. If there's no native @code{X-Face} support, Gnus
+will try to convert the @code{X-Face} header using external programs
+from the @code{pbmplus} package and friends, see below. For XEmacs it's
+faster if XEmacs has been compiled with @code{X-Face} support. The
+default action under Emacs without image support is to fork off the
+@code{display} program.
+
+On a GNU/Linux system, the @code{display} program is included in the
+ImageMagick package. For external conversion programs look for packages
+with names like @code{netpbm}, @code{libgr-progs} and @code{compface}.
+On Windows, you may use the packages @code{netpbm} and @code{compface}
+from @url{http://gnuwin32.sourceforge.net}. You need to add the
+@code{bin} directory to your @code{PATH} environment variable.
+@c In fact only the following DLLs and binaries seem to be required:
+@c compface1.dll uncompface.exe libnetpbm10.dll icontopbm.exe
+
+The variable @code{gnus-article-x-face-command} controls which programs
+are used to display the @code{X-Face} header. If this variable is a
+string, this string will be executed in a sub-shell. If it is a
+function, this function will be called with the face as the argument.
+If @code{gnus-article-x-face-too-ugly} (which is a regexp) matches the
+@code{From} header, the face will not be shown.
+
+(Note: @code{x-face} is used in the variable/function names, not
+@code{xface}).
+
+@noindent
+Face and variable:
+
+@table @code
+@item gnus-x-face
+@vindex gnus-x-face
+Face to show X-Face. The colors from this face are used as the
+foreground and background colors of the displayed X-Faces. The
+default colors are black and white.
+
+@item gnus-face-properties-alist
+@vindex gnus-face-properties-alist
+Alist of image types and properties applied to Face (@pxref{Face}) and
+X-Face images. The default value is @code{((pbm . (:face gnus-x-face))
+(png . nil))} for Emacs or @code{((xface . (:face gnus-x-face)))} for
+XEmacs. Here are examples:
+
+@lisp
+;; Specify the altitude of Face and X-Face images in the From header.
+(setq gnus-face-properties-alist
+ '((pbm . (:face gnus-x-face :ascent 80))
+ (png . (:ascent 80))))
+
+;; Show Face and X-Face images as pressed buttons.
+(setq gnus-face-properties-alist
+ '((pbm . (:face gnus-x-face :relief -2))
+ (png . (:relief -2))))
+@end lisp
+
+@pxref{Image Descriptors, ,Image Descriptors, elisp, The Emacs Lisp
+Reference Manual} for the valid properties for various image types.
+Currently, @code{pbm} is used for X-Face images and @code{png} is used
+for Face images in Emacs. Only the @code{:face} property is effective
+on the @code{xface} image type in XEmacs if it is built with the
+@samp{libcompface} library.
+@end table
+
+If you use posting styles, you can use an @code{x-face-file} entry in
+@code{gnus-posting-styles}, @xref{Posting Styles}. If you don't, Gnus
+provides a few convenience functions and variables to allow easier
+insertion of X-Face headers in outgoing messages. You also need the
+above mentioned ImageMagick, netpbm or other image conversion packages
+(depending the values of the variables below) for these functions.
+
+@findex gnus-random-x-face
+@vindex gnus-convert-pbm-to-x-face-command
+@vindex gnus-x-face-directory
+@code{gnus-random-x-face} goes through all the @samp{pbm} files in
+@code{gnus-x-face-directory} and picks one at random, and then
+converts it to the X-Face format by using the
+@code{gnus-convert-pbm-to-x-face-command} shell command. The
+@samp{pbm} files should be 48x48 pixels big. It returns the X-Face
+header data as a string.
+
+@findex gnus-insert-random-x-face-header
+@code{gnus-insert-random-x-face-header} calls
+@code{gnus-random-x-face} and inserts a @samp{X-Face} header with the
+randomly generated data.
+
+@findex gnus-x-face-from-file
+@vindex gnus-convert-image-to-x-face-command
+@code{gnus-x-face-from-file} takes a GIF file as the parameter, and then
+converts the file to X-Face format by using the
+@code{gnus-convert-image-to-x-face-command} shell command.
+
+Here's how you would typically use the first function. Put something
+like the following in your @file{~/.gnus.el} file:
+
+@lisp
+(setq message-required-news-headers
+ (nconc message-required-news-headers
+ (list '(X-Face . gnus-random-x-face))))
+@end lisp
+
+Using the last function would be something like this:
+
+@lisp
+(setq message-required-news-headers
+ (nconc message-required-news-headers
+ (list '(X-Face . (lambda ()
+ (gnus-x-face-from-file
+ "~/My-face.gif"))))))
+@end lisp
+
+
+@node Face
+@subsection Face
+@cindex face
+
+@c #### FIXME: faces and x-faces' implementations should really be harmonized.
+
+@code{Face} headers are essentially a funkier version of @code{X-Face}
+ones. They describe a 48x48 pixel colored image that's supposed to
+represent the author of the message.
+
+@cindex face
+@findex gnus-article-display-face
+The contents of a @code{Face} header must be a base64 encoded PNG image.
+See @uref{http://quimby.gnus.org/circus/face/} for the precise
+specifications.
+
+The @code{gnus-face-properties-alist} variable affects the appearance of
+displayed Face images. @xref{X-Face}.
+
+Viewing a @code{Face} header requires an Emacs that is able to display
+PNG images.
+@c Maybe add this:
+@c (if (featurep 'xemacs)
+@c (featurep 'png)
+@c (image-type-available-p 'png))
+
+Gnus provides a few convenience functions and variables to allow
+easier insertion of Face headers in outgoing messages.
+
+@findex gnus-convert-png-to-face
+@code{gnus-convert-png-to-face} takes a 48x48 PNG image, no longer than
+726 bytes long, and converts it to a face.
+
+@findex gnus-face-from-file
+@vindex gnus-convert-image-to-face-command
+@code{gnus-face-from-file} takes a JPEG file as the parameter, and then
+converts the file to Face format by using the
+@code{gnus-convert-image-to-face-command} shell command.
+
+Here's how you would typically use this function. Put something like the
+following in your @file{~/.gnus.el} file:
+
+@lisp
+(setq message-required-news-headers
+ (nconc message-required-news-headers
+ (list '(Face . (lambda ()
+ (gnus-face-from-file "~/face.jpg"))))))
+@end lisp
+
+
+@node Smileys
+@subsection Smileys
+@cindex smileys
+
+@iftex
+@iflatex
+\gnusfig{-3cm}{0.5cm}{\epsfig{figure=ps/BigFace,height=20cm}}
+\input{smiley}
+@end iflatex
+@end iftex
+
+@dfn{Smiley} is a package separate from Gnus, but since Gnus is
+currently the only package that uses Smiley, it is documented here.
+
+In short---to use Smiley in Gnus, put the following in your
+@file{~/.gnus.el} file:
+
+@lisp
+(setq gnus-treat-display-smileys t)
+@end lisp
+
+Smiley maps text smiley faces---@samp{:-)}, @samp{8-)}, @samp{:-(} and
+the like---to pictures and displays those instead of the text smiley
+faces. The conversion is controlled by a list of regexps that matches
+text and maps that to file names.
+
+@vindex smiley-regexp-alist
+The alist used is specified by the @code{smiley-regexp-alist}
+variable. The first item in each element is the regexp to be matched;
+the second element is the regexp match group that is to be replaced by
+the picture; and the third element is the name of the file to be
+displayed.
+
+The following variables customize the appearance of the smileys:
+
+@table @code
+
+@item smiley-style
+@vindex smiley-style
+Specifies the smiley style. Predefined smiley styles include
+@code{low-color} (small 13x14 pixel, three-color images), @code{medium}
+(more colorful images, 16x16 pixel), and @code{grayscale} (grayscale
+images, 14x14 pixel). The default depends on the height of the default
+face.
+
+@item smiley-data-directory
+@vindex smiley-data-directory
+Where Smiley will look for smiley faces files. You shouldn't set this
+variable anymore. Customize @code{smiley-style} instead.
+
+@item gnus-smiley-file-types
+@vindex gnus-smiley-file-types
+List of suffixes on smiley file names to try.
+
+@end table
+
+
+@node Picons
+@subsection Picons
+
+@iftex
+@iflatex
+\include{picons}
+@end iflatex
+@end iftex
+
+So@dots{} You want to slow down your news reader even more! This is a
+good way to do so. It's also a great way to impress people staring
+over your shoulder as you read news.
+
+What are Picons? To quote directly from the Picons Web site:
+
+@iftex
+@iflatex
+\margindex{}
+@end iflatex
+@end iftex
+
+@quotation
+@dfn{Picons} is short for ``personal icons''. They're small,
+constrained images used to represent users and domains on the net,
+organized into databases so that the appropriate image for a given
+e-mail address can be found. Besides users and domains, there are picon
+databases for Usenet newsgroups and weather forecasts. The picons are
+in either monochrome @code{XBM} format or color @code{XPM} and
+@code{GIF} formats.
+@end quotation
+
+@vindex gnus-picon-databases
+For instructions on obtaining and installing the picons databases,
+point your Web browser at
+@uref{http://www.cs.indiana.edu/picons/ftp/index.html}.
+
+If you are using Debian GNU/Linux, saying @samp{apt-get install
+picons.*} will install the picons where Gnus can find them.
+
+To enable displaying picons, simply make sure that
+@code{gnus-picon-databases} points to the directory containing the
+Picons databases.
+
+@vindex gnus-picon-style
+The variable @code{gnus-picon-style} controls how picons are displayed.
+If @code{inline}, the textual representation is replaced. If
+@code{right}, picons are added right to the textual representation.
+
+@vindex gnus-picon-properties
+The value of the variable @code{gnus-picon-properties} is a list of
+properties applied to picons.
+
+The following variables offer control over where things are located.
+
+@table @code
+
+@item gnus-picon-databases
+@vindex gnus-picon-databases
+The location of the picons database. This is a list of directories
+containing the @file{news}, @file{domains}, @file{users} (and so on)
+subdirectories. Defaults to @code{("/usr/lib/picon"
+"/usr/local/faces")}.
+
+@item gnus-picon-news-directories
+@vindex gnus-picon-news-directories
+List of subdirectories to search in @code{gnus-picon-databases} for
+newsgroups faces. @code{("news")} is the default.
+
+@item gnus-picon-user-directories
+@vindex gnus-picon-user-directories
+List of subdirectories to search in @code{gnus-picon-databases} for user
+faces. @code{("users" "usenix" "local" "misc")} is the default.
+
+@item gnus-picon-domain-directories
+@vindex gnus-picon-domain-directories
+List of subdirectories to search in @code{gnus-picon-databases} for
+domain name faces. Defaults to @code{("domains")}. Some people may
+want to add @samp{"unknown"} to this list.
+
+@item gnus-picon-file-types
+@vindex gnus-picon-file-types
+Ordered list of suffixes on picon file names to try. Defaults to
+@code{("xpm" "gif" "xbm")} minus those not built-in your Emacs.
+
+@item gnus-picon-inhibit-top-level-domains
+@vindex gnus-picon-inhibit-top-level-domains
+If non-@code{nil} (which is the default), don't display picons for
+things like @samp{.net} and @samp{.de}, which aren't usually very
+interesting.
+
+@end table
+
+@node Gravatars
+@subsection Gravatars
+
+@iftex
+@iflatex
+\include{gravatars}
+@end iflatex
+@end iftex
+
+A gravatar is an image registered to an e-mail address.
+
+You can submit yours on-line at @uref{http://www.gravatar.com}.
+
+The following variables offer control over how things are displayed.
+
+@table @code
+
+@item gnus-gravatar-size
+@vindex gnus-gravatar-size
+The size in pixels of gravatars. Gravatars are always square, so one
+number for the size is enough.
+
+@item gnus-gravatar-properties
+@vindex gnus-gravatar-properties
+List of image properties applied to Gravatar images.
+
+@item gnus-gravatar-too-ugly
+@vindex gnus-gravatar-too-ugly
+Regexp that matches mail addresses or names of people of which avatars
+should not be displayed, or @code{nil}. It default to the value of
+@code{gnus-article-x-face-too-ugly} (@pxref{X-Face}).
+
+@end table
+
+If you want to see them in the From field, set:
+@lisp
+(setq gnus-treat-from-gravatar 'head)
+@end lisp
+
+If you want to see them in the Cc and To fields, set:
+
+@lisp
+(setq gnus-treat-mail-gravatar 'head)
+@end lisp
+
+
+@node XVarious
+@subsection Various XEmacs Variables
+
+@table @code
+@item gnus-xmas-glyph-directory
+@vindex gnus-xmas-glyph-directory
+This is where Gnus will look for pictures. Gnus will normally
+auto-detect this directory, but you may set it manually if you have an
+unusual directory structure.
+
+@item gnus-xmas-modeline-glyph
+@vindex gnus-xmas-modeline-glyph
+A glyph displayed in all Gnus mode lines. It is a tiny gnu head by
+default.
+
+@end table
+
+@subsubsection Toolbar
+
+@table @code
+
+@item gnus-use-toolbar
+@vindex gnus-use-toolbar
+This variable specifies the position to display the toolbar. If
+@code{nil}, don't display toolbars. If it is non-@code{nil}, it should
+be one of the symbols @code{default}, @code{top}, @code{bottom},
+@code{right}, and @code{left}. @code{default} means to use the default
+toolbar, the rest mean to display the toolbar on the place which those
+names show. The default is @code{default}.
+
+@item gnus-toolbar-thickness
+@vindex gnus-toolbar-thickness
+Cons of the height and the width specifying the thickness of a toolbar.
+The height is used for the toolbar displayed on the top or the bottom,
+the width is used for the toolbar displayed on the right or the left.
+The default is that of the default toolbar.
+
+@item gnus-group-toolbar
+@vindex gnus-group-toolbar
+The toolbar in the group buffer.
+
+@item gnus-summary-toolbar
+@vindex gnus-summary-toolbar
+The toolbar in the summary buffer.
+
+@item gnus-summary-mail-toolbar
+@vindex gnus-summary-mail-toolbar
+The toolbar in the summary buffer of mail groups.
+
+@end table
+
+@iftex
+@iflatex
+\margindex{}
+@end iflatex
+@end iftex
+
+
+@node Fuzzy Matching
+@section Fuzzy Matching
+@cindex fuzzy matching
+
+Gnus provides @dfn{fuzzy matching} of @code{Subject} lines when doing
+things like scoring, thread gathering and thread comparison.
+
+As opposed to regular expression matching, fuzzy matching is very fuzzy.
+It's so fuzzy that there's not even a definition of what @dfn{fuzziness}
+means, and the implementation has changed over time.
+
+Basically, it tries to remove all noise from lines before comparing.
+@samp{Re: }, parenthetical remarks, white space, and so on, are filtered
+out of the strings before comparing the results. This often leads to
+adequate results---even when faced with strings generated by text
+manglers masquerading as newsreaders.
+
+
+@node Thwarting Email Spam
+@section Thwarting Email Spam
+@cindex email spam
+@cindex spam
+@cindex UCE
+@cindex unsolicited commercial email
+
+In these last days of the Usenet, commercial vultures are hanging about
+and grepping through news like crazy to find email addresses they can
+foist off their scams and products to. As a reaction to this, many
+people have started putting nonsense addresses into their @code{From}
+lines. I think this is counterproductive---it makes it difficult for
+people to send you legitimate mail in response to things you write, as
+well as making it difficult to see who wrote what. This rewriting may
+perhaps be a bigger menace than the unsolicited commercial email itself
+in the end.
+
+The biggest problem I have with email spam is that it comes in under
+false pretenses. I press @kbd{g} and Gnus merrily informs me that I
+have 10 new emails. I say ``Golly gee! Happy is me!'' and select the
+mail group, only to find two pyramid schemes, seven advertisements
+(``New! Miracle tonic for growing full, lustrous hair on your toes!'')
+and one mail asking me to repent and find some god.
+
+This is annoying. Here's what you can do about it.
+
+@menu
+* The problem of spam:: Some background, and some solutions
+* Anti-Spam Basics:: Simple steps to reduce the amount of spam.
+* SpamAssassin:: How to use external anti-spam tools.
+* Hashcash:: Reduce spam by burning CPU time.
+@end menu
+
+@node The problem of spam
+@subsection The problem of spam
+@cindex email spam
+@cindex spam filtering approaches
+@cindex filtering approaches, spam
+@cindex UCE
+@cindex unsolicited commercial email
+
+First, some background on spam.
+
+If you have access to e-mail, you are familiar with spam (technically
+termed @acronym{UCE}, Unsolicited Commercial E-mail). Simply put, it
+exists because e-mail delivery is very cheap compared to paper mail,
+so only a very small percentage of people need to respond to an UCE to
+make it worthwhile to the advertiser. Ironically, one of the most
+common spams is the one offering a database of e-mail addresses for
+further spamming. Senders of spam are usually called @emph{spammers},
+but terms like @emph{vermin}, @emph{scum}, @emph{sociopaths}, and
+@emph{morons} are in common use as well.
+
+Spam comes from a wide variety of sources. It is simply impossible to
+dispose of all spam without discarding useful messages. A good
+example is the TMDA system, which requires senders
+unknown to you to confirm themselves as legitimate senders before
+their e-mail can reach you. Without getting into the technical side
+of TMDA, a downside is clearly that e-mail from legitimate sources may
+be discarded if those sources can't or won't confirm themselves
+through the TMDA system. Another problem with TMDA is that it
+requires its users to have a basic understanding of e-mail delivery
+and processing.
+
+The simplest approach to filtering spam is filtering, at the mail
+server or when you sort through incoming mail. If you get 200 spam
+messages per day from @samp{random-address@@vmadmin.com}, you block
+@samp{vmadmin.com}. If you get 200 messages about @samp{VIAGRA}, you
+discard all messages with @samp{VIAGRA} in the message. If you get
+lots of spam from Bulgaria, for example, you try to filter all mail
+from Bulgarian IPs.
+
+This, unfortunately, is a great way to discard legitimate e-mail. The
+risks of blocking a whole country (Bulgaria, Norway, Nigeria, China,
+etc.)@: or even a continent (Asia, Africa, Europe, etc.)@: from contacting
+you should be obvious, so don't do it if you have the choice.
+
+In another instance, the very informative and useful RISKS digest has
+been blocked by overzealous mail filters because it @strong{contained}
+words that were common in spam messages. Nevertheless, in isolated
+cases, with great care, direct filtering of mail can be useful.
+
+Another approach to filtering e-mail is the distributed spam
+processing, for instance DCC implements such a system. In essence,
+@var{N} systems around the world agree that a machine @var{X} in
+Ghana, Estonia, or California is sending out spam e-mail, and these
+@var{N} systems enter @var{X} or the spam e-mail from @var{X} into a
+database. The criteria for spam detection vary---it may be the number
+of messages sent, the content of the messages, and so on. When a user
+of the distributed processing system wants to find out if a message is
+spam, he consults one of those @var{N} systems.
+
+Distributed spam processing works very well against spammers that send
+a large number of messages at once, but it requires the user to set up
+fairly complicated checks. There are commercial and free distributed
+spam processing systems. Distributed spam processing has its risks as
+well. For instance legitimate e-mail senders have been accused of
+sending spam, and their web sites and mailing lists have been shut
+down for some time because of the incident.
+
+The statistical approach to spam filtering is also popular. It is
+based on a statistical analysis of previous spam messages. Usually
+the analysis is a simple word frequency count, with perhaps pairs of
+words or 3-word combinations thrown into the mix. Statistical
+analysis of spam works very well in most of the cases, but it can
+classify legitimate e-mail as spam in some cases. It takes time to
+run the analysis, the full message must be analyzed, and the user has
+to store the database of spam analysis. Statistical analysis on the
+server is gaining popularity. This has the advantage of letting the
+user Just Read Mail, but has the disadvantage that it's harder to tell
+the server that it has misclassified mail.
+
+Fighting spam is not easy, no matter what anyone says. There is no
+magic switch that will distinguish Viagra ads from Mom's e-mails.
+Even people are having a hard time telling spam apart from non-spam,
+because spammers are actively looking to fool us into thinking they
+are Mom, essentially. Spamming is irritating, irresponsible, and
+idiotic behavior from a bunch of people who think the world owes them
+a favor. We hope the following sections will help you in fighting the
+spam plague.
+
+@node Anti-Spam Basics
+@subsection Anti-Spam Basics
+@cindex email spam
+@cindex spam
+@cindex UCE
+@cindex unsolicited commercial email
+
+One way of dealing with spam is having Gnus split out all spam into a
+@samp{spam} mail group (@pxref{Splitting Mail}).
+
+First, pick one (1) valid mail address that you can be reached at, and
+put it in your @code{From} header of all your news articles. (I've
+chosen @samp{larsi@@trym.ifi.uio.no}, but for many addresses on the form
+@samp{larsi+usenet@@ifi.uio.no} will be a better choice. Ask your
+sysadmin whether your sendmail installation accepts keywords in the local
+part of the mail address.)
+
+@lisp
+(setq message-default-news-headers
+ "From: Lars Magne Ingebrigtsen <larsi@@trym.ifi.uio.no>\n")
+@end lisp
+
+Then put the following split rule in @code{nnmail-split-fancy}
+(@pxref{Fancy Mail Splitting}):
+
+@lisp
+(...
+ (to "larsi@@trym.ifi.uio.no"
+ (| ("subject" "re:.*" "misc")
+ ("references" ".*@@.*" "misc")
+ "spam"))
+ ...)
+@end lisp
+
+This says that all mail to this address is suspect, but if it has a
+@code{Subject} that starts with a @samp{Re:} or has a @code{References}
+header, it's probably ok. All the rest goes to the @samp{spam} group.
+(This idea probably comes from Tim Pierce.)
+
+In addition, many mail spammers talk directly to your @acronym{SMTP} server
+and do not include your email address explicitly in the @code{To}
+header. Why they do this is unknown---perhaps it's to thwart this
+thwarting scheme? In any case, this is trivial to deal with---you just
+put anything not addressed to you in the @samp{spam} group by ending
+your fancy split rule in this way:
+
+@lisp
+(
+ ...
+ (to "larsi" "misc")
+ "spam")
+@end lisp
+
+In my experience, this will sort virtually everything into the right
+group. You still have to check the @samp{spam} group from time to time to
+check for legitimate mail, though. If you feel like being a good net
+citizen, you can even send off complaints to the proper authorities on
+each unsolicited commercial email---at your leisure.
+
+This works for me. It allows people an easy way to contact me (they can
+just press @kbd{r} in the usual way), and I'm not bothered at all with
+spam. It's a win-win situation. Forging @code{From} headers to point
+to non-existent domains is yucky, in my opinion.
+
+Be careful with this approach. Spammers are wise to it.
+
+
+@node SpamAssassin
+@subsection SpamAssassin, Vipul's Razor, DCC, etc
+@cindex SpamAssassin
+@cindex Vipul's Razor
+@cindex DCC
+
+The days where the hints in the previous section were sufficient in
+avoiding spam are coming to an end. There are many tools out there
+that claim to reduce the amount of spam you get. This section could
+easily become outdated fast, as new products replace old, but
+fortunately most of these tools seem to have similar interfaces. Even
+though this section will use SpamAssassin as an example, it should be
+easy to adapt it to most other tools.
+
+Note that this section does not involve the @code{spam.el} package,
+which is discussed in the next section. If you don't care for all
+the features of @code{spam.el}, you can make do with these simple
+recipes.
+
+If the tool you are using is not installed on the mail server, you
+need to invoke it yourself. Ideas on how to use the
+@code{:postscript} mail source parameter (@pxref{Mail Source
+Specifiers}) follow.
+
+@lisp
+(setq mail-sources
+ '((file :prescript "formail -bs spamassassin < /var/mail/%u")
+ (pop :user "jrl"
+ :server "pophost"
+ :postscript
+ "mv %t /tmp/foo; formail -bs spamc < /tmp/foo > %t")))
+@end lisp
+
+Once you manage to process your incoming spool somehow, thus making
+the mail contain, e.g., a header indicating it is spam, you are ready to
+filter it out. Using normal split methods (@pxref{Splitting Mail}):
+
+@lisp
+(setq nnmail-split-methods '(("spam" "^X-Spam-Flag: YES")
+ ...))
+@end lisp
+
+Or using fancy split methods (@pxref{Fancy Mail Splitting}):
+
+@lisp
+(setq nnmail-split-methods 'nnmail-split-fancy
+ nnmail-split-fancy '(| ("X-Spam-Flag" "YES" "spam")
+ ...))
+@end lisp
+
+Some people might not like the idea of piping the mail through various
+programs using a @code{:prescript} (if some program is buggy, you
+might lose all mail). If you are one of them, another solution is to
+call the external tools during splitting. Example fancy split method:
+
+@lisp
+(setq nnmail-split-fancy '(| (: kevin-spamassassin)
+ ...))
+(defun kevin-spamassassin ()
+ (save-excursion
+ (save-restriction
+ (widen)
+ (if (eq 1 (call-process-region (point-min) (point-max)
+ "spamc" nil nil nil "-c"))
+ "spam"))))
+@end lisp
+
+Note that with the nnimap back end, message bodies will not be
+downloaded by default. You need to set
+@code{nnimap-split-download-body} to @code{t} to do that
+(@pxref{Client-Side IMAP Splitting}).
+
+That is about it. As some spam is likely to get through anyway, you
+might want to have a nifty function to call when you happen to read
+spam. And here is the nifty function:
+
+@lisp
+(defun my-gnus-raze-spam ()
+ "Submit SPAM to Vipul's Razor, then mark it as expirable."
+ (interactive)
+ (gnus-summary-save-in-pipe "razor-report -f -d" t)
+ (gnus-summary-mark-as-expirable 1))
+@end lisp
+
+@node Hashcash
+@subsection Hashcash
+@cindex hashcash
+
+A novel technique to fight spam is to require senders to do something
+costly and demonstrably unique for each message they send. This has
+the obvious drawback that you cannot rely on everyone in the world
+using this technique, since it is not part of the Internet standards,
+but it may be useful in smaller communities.
+
+While the tools in the previous section work well in practice, they
+work only because the tools are constantly maintained and updated as
+new form of spam appears. This means that a small percentage of spam
+will always get through. It also means that somewhere, someone needs
+to read lots of spam to update these tools. Hashcash avoids that, but
+instead prefers that everyone you contact through e-mail supports the
+scheme. You can view the two approaches as pragmatic vs dogmatic.
+The approaches have their own advantages and disadvantages, but as
+often in the real world, a combination of them is stronger than either
+one of them separately.
+
+@cindex X-Hashcash
+The ``something costly'' is to burn CPU time, more specifically to
+compute a hash collision up to a certain number of bits. The
+resulting hashcash cookie is inserted in a @samp{X-Hashcash:} header.
+For more details, and for the external application @code{hashcash} you
+need to install to use this feature, see
+@uref{http://www.hashcash.org/}. Even more information can be found
+at @uref{http://www.camram.org/}.
+
+If you wish to generate hashcash for each message you send, you can
+customize @code{message-generate-hashcash} (@pxref{Mail Headers, ,Mail
+Headers,message, The Message Manual}), as in:
+
+@lisp
+(setq message-generate-hashcash t)
+@end lisp
+
+You will need to set up some additional variables as well:
+
+@table @code
+
+@item hashcash-default-payment
+@vindex hashcash-default-payment
+This variable indicates the default number of bits the hash collision
+should consist of. By default this is 20. Suggested useful values
+include 17 to 29.
+
+@item hashcash-payment-alist
+@vindex hashcash-payment-alist
+Some receivers may require you to spend burn more CPU time than the
+default. This variable contains a list of @samp{(@var{addr}
+@var{amount})} cells, where @var{addr} is the receiver (email address
+or newsgroup) and @var{amount} is the number of bits in the collision
+that is needed. It can also contain @samp{(@var{addr} @var{string}
+@var{amount})} cells, where the @var{string} is the string to use
+(normally the email address or newsgroup name is used).
+
+@item hashcash-path
+@vindex hashcash-path
+Where the @code{hashcash} binary is installed. This variable should
+be automatically set by @code{executable-find}, but if it's @code{nil}
+(usually because the @code{hashcash} binary is not in your path)
+you'll get a warning when you check hashcash payments and an error
+when you generate hashcash payments.
+
+@end table
+
+Gnus can verify hashcash cookies, although this can also be done by
+hand customized mail filtering scripts. To verify a hashcash cookie
+in a message, use the @code{mail-check-payment} function in the
+@code{hashcash.el} library. You can also use the @code{spam.el}
+package with the @code{spam-use-hashcash} back end to validate hashcash
+cookies in incoming mail and filter mail accordingly (@pxref{Anti-spam
+Hashcash Payments}).
+
+@node Spam Package
+@section Spam Package
+@cindex spam filtering
+@cindex spam
+
+The Spam package provides Gnus with a centralized mechanism for
+detecting and filtering spam. It filters new mail, and processes
+messages according to whether they are spam or ham. (@dfn{Ham} is the
+name used throughout this manual to indicate non-spam messages.)
+
+@menu
+* Spam Package Introduction::
+* Filtering Incoming Mail::
+* Detecting Spam in Groups::
+* Spam and Ham Processors::
+* Spam Package Configuration Examples::
+* Spam Back Ends::
+* Extending the Spam package::
+* Spam Statistics Package::
+@end menu
+
+@node Spam Package Introduction
+@subsection Spam Package Introduction
+@cindex spam filtering
+@cindex spam filtering sequence of events
+@cindex spam
+
+You must read this section to understand how the Spam package works.
+Do not skip, speed-read, or glance through this section.
+
+Make sure you read the section on the @code{spam.el} sequence of
+events. See @xref{Extending the Spam package}.
+
+@cindex spam-initialize
+@vindex spam-use-stat
+To use the Spam package, you @strong{must} first run the function
+@code{spam-initialize}:
+
+@example
+(spam-initialize)
+@end example
+
+This autoloads @code{spam.el} and installs the various hooks necessary
+to let the Spam package do its job. In order to make use of the Spam
+package, you have to set up certain group parameters and variables,
+which we will describe below. All of the variables controlling the
+Spam package can be found in the @samp{spam} customization group.
+
+There are two ``contact points'' between the Spam package and the rest
+of Gnus: checking new mail for spam, and leaving a group.
+
+Checking new mail for spam is done in one of two ways: while splitting
+incoming mail, or when you enter a group.
+
+The first way, checking for spam while splitting incoming mail, is
+suited to mail back ends such as @code{nnml} or @code{nnimap}, where
+new mail appears in a single spool file. The Spam package processes
+incoming mail, and sends mail considered to be spam to a designated
+``spam'' group. @xref{Filtering Incoming Mail}.
+
+The second way is suited to back ends such as @code{nntp}, which have
+no incoming mail spool, or back ends where the server is in charge of
+splitting incoming mail. In this case, when you enter a Gnus group,
+the unseen or unread messages in that group are checked for spam.
+Detected spam messages are marked as spam. @xref{Detecting Spam in
+Groups}.
+
+@cindex spam back ends
+In either case, you have to tell the Spam package what method to use
+to detect spam messages. There are several methods, or @dfn{spam back
+ends} (not to be confused with Gnus back ends!) to choose from: spam
+``blacklists'' and ``whitelists'', dictionary-based filters, and so
+forth. @xref{Spam Back Ends}.
+
+In the Gnus summary buffer, messages that have been identified as spam
+always appear with a @samp{$} symbol.
+
+The Spam package divides Gnus groups into three categories: ham
+groups, spam groups, and unclassified groups. You should mark each of
+the groups you subscribe to as either a ham group or a spam group,
+using the @code{spam-contents} group parameter (@pxref{Group
+Parameters}). Spam groups have a special property: when you enter a
+spam group, all unseen articles are marked as spam. Thus, mail split
+into a spam group is automatically marked as spam.
+
+Identifying spam messages is only half of the Spam package's job. The
+second half comes into play whenever you exit a group buffer. At this
+point, the Spam package does several things:
+
+First, it calls @dfn{spam and ham processors} to process the articles
+according to whether they are spam or ham. There is a pair of spam
+and ham processors associated with each spam back end, and what the
+processors do depends on the back end. At present, the main role of
+spam and ham processors is for dictionary-based spam filters: they add
+the contents of the messages in the group to the filter's dictionary,
+to improve its ability to detect future spam. The @code{spam-process}
+group parameter specifies what spam processors to use. @xref{Spam and
+Ham Processors}.
+
+If the spam filter failed to mark a spam message, you can mark it
+yourself, so that the message is processed as spam when you exit the
+group:
+
+@table @kbd
+@item $
+@itemx M-d
+@itemx M s x
+@itemx S x
+@kindex $ (Summary)
+@kindex M-d (Summary)
+@kindex S x (Summary)
+@kindex M s x (Summary)
+@findex gnus-summary-mark-as-spam
+@findex gnus-summary-mark-as-spam
+Mark current article as spam, showing it with the @samp{$} mark
+(@code{gnus-summary-mark-as-spam}).
+@end table
+
+@noindent
+Similarly, you can unmark an article if it has been erroneously marked
+as spam. @xref{Setting Marks}.
+
+Normally, a ham message found in a non-ham group is not processed as
+ham---the rationale is that it should be moved into a ham group for
+further processing (see below). However, you can force these articles
+to be processed as ham by setting
+@code{spam-process-ham-in-spam-groups} and
+@code{spam-process-ham-in-nonham-groups}.
+
+@vindex gnus-ham-process-destinations
+@vindex gnus-spam-process-destinations
+The second thing that the Spam package does when you exit a group is
+to move ham articles out of spam groups, and spam articles out of ham
+groups. Ham in a spam group is moved to the group specified by the
+variable @code{gnus-ham-process-destinations}, or the group parameter
+@code{ham-process-destination}. Spam in a ham group is moved to the
+group specified by the variable @code{gnus-spam-process-destinations},
+or the group parameter @code{spam-process-destination}. If these
+variables are not set, the articles are left in their current group.
+If an article cannot be moved (e.g., with a read-only backend such
+as @acronym{NNTP}), it is copied.
+
+If an article is moved to another group, it is processed again when
+you visit the new group. Normally, this is not a problem, but if you
+want each article to be processed only once, load the
+@code{gnus-registry.el} package and set the variable
+@code{spam-log-to-registry} to @code{t}. @xref{Spam Package
+Configuration Examples}.
+
+Normally, spam groups ignore @code{gnus-spam-process-destinations}.
+However, if you set @code{spam-move-spam-nonspam-groups-only} to
+@code{nil}, spam will also be moved out of spam groups, depending on
+the @code{spam-process-destination} parameter.
+
+The final thing the Spam package does is to mark spam articles as
+expired, which is usually the right thing to do.
+
+If all this seems confusing, don't worry. Soon it will be as natural
+as typing Lisp one-liners on a neural interface@dots{} err, sorry, that's
+50 years in the future yet. Just trust us, it's not so bad.
+
+@node Filtering Incoming Mail
+@subsection Filtering Incoming Mail
+@cindex spam filtering
+@cindex spam filtering incoming mail
+@cindex spam
+
+To use the Spam package to filter incoming mail, you must first set up
+fancy mail splitting. @xref{Fancy Mail Splitting}. The Spam package
+defines a special splitting function that you can add to your fancy
+split variable (either @code{nnmail-split-fancy} or
+@code{nnimap-split-fancy}, depending on your mail back end):
+
+@example
+(: spam-split)
+@end example
+
+@vindex spam-split-group
+@noindent
+The @code{spam-split} function scans incoming mail according to your
+chosen spam back end(s), and sends messages identified as spam to a
+spam group. By default, the spam group is a group named @samp{spam},
+but you can change this by customizing @code{spam-split-group}. Make
+sure the contents of @code{spam-split-group} are an unqualified group
+name. For instance, in an @code{nnimap} server @samp{your-server},
+the value @samp{spam} means @samp{nnimap+your-server:spam}. The value
+@samp{nnimap+server:spam} is therefore wrong---it gives the group
+@samp{nnimap+your-server:nnimap+server:spam}.
+
+@code{spam-split} does not modify the contents of messages in any way.
+
+@vindex nnimap-split-download-body
+Note for IMAP users: if you use the @code{spam-check-bogofilter},
+@code{spam-check-ifile}, and @code{spam-check-stat} spam back ends,
+you should also set the variable @code{nnimap-split-download-body} to
+@code{t}. These spam back ends are most useful when they can ``scan''
+the full message body. By default, the nnimap back end only retrieves
+the message headers; @code{nnimap-split-download-body} tells it to
+retrieve the message bodies as well. We don't set this by default
+because it will slow @acronym{IMAP} down, and that is not an
+appropriate decision to make on behalf of the user. @xref{Client-Side
+IMAP Splitting}.
+
+You have to specify one or more spam back ends for @code{spam-split}
+to use, by setting the @code{spam-use-*} variables. @xref{Spam Back
+Ends}. Normally, @code{spam-split} simply uses all the spam back ends
+you enabled in this way. However, you can tell @code{spam-split} to
+use only some of them. Why this is useful? Suppose you are using the
+@code{spam-use-regex-headers} and @code{spam-use-blackholes} spam back
+ends, and the following split rule:
+
+@example
+ nnimap-split-fancy '(|
+ (any "ding" "ding")
+ (: spam-split)
+ ;; @r{default mailbox}
+ "mail")
+@end example
+
+@noindent
+The problem is that you want all ding messages to make it to the ding
+folder. But that will let obvious spam (for example, spam detected by
+SpamAssassin, and @code{spam-use-regex-headers}) through, when it's
+sent to the ding list. On the other hand, some messages to the ding
+list are from a mail server in the blackhole list, so the invocation
+of @code{spam-split} can't be before the ding rule.
+
+The solution is to let SpamAssassin headers supersede ding rules, and
+perform the other @code{spam-split} rules (including a second
+invocation of the regex-headers check) after the ding rule. This is
+done by passing a parameter to @code{spam-split}:
+
+@example
+nnimap-split-fancy
+ '(|
+ ;; @r{spam detected by @code{spam-use-regex-headers} goes to @samp{regex-spam}}
+ (: spam-split "regex-spam" 'spam-use-regex-headers)
+ (any "ding" "ding")
+ ;; @r{all other spam detected by spam-split goes to @code{spam-split-group}}
+ (: spam-split)
+ ;; @r{default mailbox}
+ "mail")
+@end example
+
+@noindent
+This lets you invoke specific @code{spam-split} checks depending on
+your particular needs, and target the results of those checks to a
+particular spam group. You don't have to throw all mail into all the
+spam tests. Another reason why this is nice is that messages to
+mailing lists you have rules for don't have to have resource-intensive
+blackhole checks performed on them. You could also specify different
+spam checks for your nnmail split vs. your nnimap split. Go crazy.
+
+You should set the @code{spam-use-*} variables for whatever spam back
+ends you intend to use. The reason is that when loading
+@file{spam.el}, some conditional loading is done depending on what
+@code{spam-use-xyz} variables you have set. @xref{Spam Back Ends}.
+
+@c @emph{TODO: spam.el needs to provide a uniform way of training all the
+@c statistical databases. Some have that functionality built-in, others
+@c don't.}
+
+@node Detecting Spam in Groups
+@subsection Detecting Spam in Groups
+
+To detect spam when visiting a group, set the group's
+@code{spam-autodetect} and @code{spam-autodetect-methods} group
+parameters. These are accessible with @kbd{G c} or @kbd{G p}, as
+usual (@pxref{Group Parameters}).
+
+You should set the @code{spam-use-*} variables for whatever spam back
+ends you intend to use. The reason is that when loading
+@file{spam.el}, some conditional loading is done depending on what
+@code{spam-use-xyz} variables you have set.
+
+By default, only unseen articles are processed for spam. You can
+force Gnus to recheck all messages in the group by setting the
+variable @code{spam-autodetect-recheck-messages} to @code{t}.
+
+If you use the @code{spam-autodetect} method of checking for spam, you
+can specify different spam detection methods for different groups.
+For instance, the @samp{ding} group may have @code{spam-use-BBDB} as
+the autodetection method, while the @samp{suspect} group may have the
+@code{spam-use-blacklist} and @code{spam-use-bogofilter} methods
+enabled. Unlike with @code{spam-split}, you don't have any control
+over the @emph{sequence} of checks, but this is probably unimportant.
+
+@node Spam and Ham Processors
+@subsection Spam and Ham Processors
+@cindex spam filtering
+@cindex spam filtering variables
+@cindex spam variables
+@cindex spam
+
+@vindex gnus-spam-process-newsgroups
+Spam and ham processors specify special actions to take when you exit
+a group buffer. Spam processors act on spam messages, and ham
+processors on ham messages. At present, the main role of these
+processors is to update the dictionaries of dictionary-based spam back
+ends such as Bogofilter (@pxref{Bogofilter}) and the Spam Statistics
+package (@pxref{Spam Statistics Filtering}).
+
+The spam and ham processors that apply to each group are determined by
+the group's@code{spam-process} group parameter. If this group
+parameter is not defined, they are determined by the variable
+@code{gnus-spam-process-newsgroups}.
+
+@vindex gnus-spam-newsgroup-contents
+Gnus learns from the spam you get. You have to collect your spam in
+one or more spam groups, and set or customize the variable
+@code{spam-junk-mailgroups} as appropriate. You can also declare
+groups to contain spam by setting their group parameter
+@code{spam-contents} to @code{gnus-group-spam-classification-spam}, or
+by customizing the corresponding variable
+@code{gnus-spam-newsgroup-contents}. The @code{spam-contents} group
+parameter and the @code{gnus-spam-newsgroup-contents} variable can
+also be used to declare groups as @emph{ham} groups if you set their
+classification to @code{gnus-group-spam-classification-ham}. If
+groups are not classified by means of @code{spam-junk-mailgroups},
+@code{spam-contents}, or @code{gnus-spam-newsgroup-contents}, they are
+considered @emph{unclassified}. All groups are unclassified by
+default.
+
+@vindex gnus-spam-mark
+@cindex $
+In spam groups, all messages are considered to be spam by default:
+they get the @samp{$} mark (@code{gnus-spam-mark}) when you enter the
+group. If you have seen a message, had it marked as spam, then
+unmarked it, it won't be marked as spam when you enter the group
+thereafter. You can disable that behavior, so all unread messages
+will get the @samp{$} mark, if you set the
+@code{spam-mark-only-unseen-as-spam} parameter to @code{nil}. You
+should remove the @samp{$} mark when you are in the group summary
+buffer for every message that is not spam after all. To remove the
+@samp{$} mark, you can use @kbd{M-u} to ``unread'' the article, or
+@kbd{d} for declaring it read the non-spam way. When you leave a
+group, all spam-marked (@samp{$}) articles are sent to a spam
+processor which will study them as spam samples.
+
+Messages may also be deleted in various other ways, and unless
+@code{ham-marks} group parameter gets overridden below, marks @samp{R}
+and @samp{r} for default read or explicit delete, marks @samp{X} and
+@samp{K} for automatic or explicit kills, as well as mark @samp{Y} for
+low scores, are all considered to be associated with articles which
+are not spam. This assumption might be false, in particular if you
+use kill files or score files as means for detecting genuine spam, you
+should then adjust the @code{ham-marks} group parameter.
+
+@defvar ham-marks
+You can customize this group or topic parameter to be the list of
+marks you want to consider ham. By default, the list contains the
+deleted, read, killed, kill-filed, and low-score marks (the idea is
+that these articles have been read, but are not spam). It can be
+useful to also include the tick mark in the ham marks. It is not
+recommended to make the unread mark a ham mark, because it normally
+indicates a lack of classification. But you can do it, and we'll be
+happy for you.
+@end defvar
+
+@defvar spam-marks
+You can customize this group or topic parameter to be the list of
+marks you want to consider spam. By default, the list contains only
+the spam mark. It is not recommended to change that, but you can if
+you really want to.
+@end defvar
+
+When you leave @emph{any} group, regardless of its
+@code{spam-contents} classification, all spam-marked articles are sent
+to a spam processor, which will study these as spam samples. If you
+explicit kill a lot, you might sometimes end up with articles marked
+@samp{K} which you never saw, and which might accidentally contain
+spam. Best is to make sure that real spam is marked with @samp{$},
+and nothing else.
+
+@vindex gnus-ham-process-destinations
+When you leave a @emph{spam} group, all spam-marked articles are
+marked as expired after processing with the spam processor. This is
+not done for @emph{unclassified} or @emph{ham} groups. Also, any
+@strong{ham} articles in a spam group will be moved to a location
+determined by either the @code{ham-process-destination} group
+parameter or a match in the @code{gnus-ham-process-destinations}
+variable, which is a list of regular expressions matched with group
+names (it's easiest to customize this variable with @kbd{M-x
+customize-variable @key{RET} gnus-ham-process-destinations}). Each
+group name list is a standard Lisp list, if you prefer to customize
+the variable manually. If the @code{ham-process-destination}
+parameter is not set, ham articles are left in place. If the
+@code{spam-mark-ham-unread-before-move-from-spam-group} parameter is
+set, the ham articles are marked as unread before being moved.
+
+If ham can not be moved---because of a read-only back end such as
+@acronym{NNTP}, for example, it will be copied.
+
+Note that you can use multiples destinations per group or regular
+expression! This enables you to send your ham to a regular mail
+group and to a @emph{ham training} group.
+
+When you leave a @emph{ham} group, all ham-marked articles are sent to
+a ham processor, which will study these as non-spam samples.
+
+@vindex spam-process-ham-in-spam-groups
+By default the variable @code{spam-process-ham-in-spam-groups} is
+@code{nil}. Set it to @code{t} if you want ham found in spam groups
+to be processed. Normally this is not done, you are expected instead
+to send your ham to a ham group and process it there.
+
+@vindex spam-process-ham-in-nonham-groups
+By default the variable @code{spam-process-ham-in-nonham-groups} is
+@code{nil}. Set it to @code{t} if you want ham found in non-ham (spam
+or unclassified) groups to be processed. Normally this is not done,
+you are expected instead to send your ham to a ham group and process
+it there.
+
+@vindex gnus-spam-process-destinations
+When you leave a @emph{ham} or @emph{unclassified} group, all
+@strong{spam} articles are moved to a location determined by either
+the @code{spam-process-destination} group parameter or a match in the
+@code{gnus-spam-process-destinations} variable, which is a list of
+regular expressions matched with group names (it's easiest to
+customize this variable with @kbd{M-x customize-variable @key{RET}
+gnus-spam-process-destinations}). Each group name list is a standard
+Lisp list, if you prefer to customize the variable manually. If the
+@code{spam-process-destination} parameter is not set, the spam
+articles are only expired. The group name is fully qualified, meaning
+that if you see @samp{nntp:servername} before the group name in the
+group buffer then you need it here as well.
+
+If spam can not be moved---because of a read-only back end such as
+@acronym{NNTP}, for example, it will be copied.
+
+Note that you can use multiples destinations per group or regular
+expression! This enables you to send your spam to multiple @emph{spam
+training} groups.
+
+@vindex spam-log-to-registry
+The problem with processing ham and spam is that Gnus doesn't track
+this processing by default. Enable the @code{spam-log-to-registry}
+variable so @code{spam.el} will use @code{gnus-registry.el} to track
+what articles have been processed, and avoid processing articles
+multiple times. Keep in mind that if you limit the number of registry
+entries, this won't work as well as it does without a limit.
+
+@vindex spam-mark-only-unseen-as-spam
+Set this variable if you want only unseen articles in spam groups to
+be marked as spam. By default, it is set. If you set it to
+@code{nil}, unread articles will also be marked as spam.
+
+@vindex spam-mark-ham-unread-before-move-from-spam-group
+Set this variable if you want ham to be unmarked before it is moved
+out of the spam group. This is very useful when you use something
+like the tick mark @samp{!} to mark ham---the article will be placed
+in your @code{ham-process-destination}, unmarked as if it came fresh
+from the mail server.
+
+@vindex spam-autodetect-recheck-messages
+When autodetecting spam, this variable tells @code{spam.el} whether
+only unseen articles or all unread articles should be checked for
+spam. It is recommended that you leave it off.
+
+@node Spam Package Configuration Examples
+@subsection Spam Package Configuration Examples
+@cindex spam filtering
+@cindex spam filtering configuration examples
+@cindex spam configuration examples
+@cindex spam
+
+@subsubheading Ted's setup
+
+From Ted Zlatanov <tzz@@lifelogs.com>.
+@example
+;; @r{for @code{gnus-registry-split-fancy-with-parent} and spam autodetection}
+;; @r{see @file{gnus-registry.el} for more information}
+(gnus-registry-initialize)
+(spam-initialize)
+
+(setq
+ spam-log-to-registry t ; @r{for spam autodetection}
+ spam-use-BBDB t
+ spam-use-regex-headers t ; @r{catch X-Spam-Flag (SpamAssassin)}
+ ;; @r{all groups with @samp{spam} in the name contain spam}
+ gnus-spam-newsgroup-contents
+ '(("spam" gnus-group-spam-classification-spam))
+ ;; @r{see documentation for these}
+ spam-move-spam-nonspam-groups-only nil
+ spam-mark-only-unseen-as-spam t
+ spam-mark-ham-unread-before-move-from-spam-group t
+ ;; @r{understand what this does before you copy it to your own setup!}
+ ;; @r{for nnimap you'll probably want to set nnimap-split-methods, see the manual}
+ nnimap-split-fancy '(|
+ ;; @r{trace references to parents and put in their group}
+ (: gnus-registry-split-fancy-with-parent)
+ ;; @r{this will catch server-side SpamAssassin tags}
+ (: spam-split 'spam-use-regex-headers)
+ (any "ding" "ding")
+ ;; @r{note that spam by default will go to @samp{spam}}
+ (: spam-split)
+ ;; @r{default mailbox}
+ "mail"))
+
+;; @r{my parameters, set with @kbd{G p}}
+
+;; @r{all nnml groups, and all nnimap groups except}
+;; @r{@samp{nnimap+mail.lifelogs.com:train} and}
+;; @r{@samp{nnimap+mail.lifelogs.com:spam}: any spam goes to nnimap training,}
+;; @r{because it must have been detected manually}
+
+((spam-process-destination . "nnimap+mail.lifelogs.com:train"))
+
+;; @r{all @acronym{NNTP} groups}
+;; @r{autodetect spam with the blacklist and ham with the BBDB}
+((spam-autodetect-methods spam-use-blacklist spam-use-BBDB)
+;; @r{send all spam to the training group}
+ (spam-process-destination . "nnimap+mail.lifelogs.com:train"))
+
+;; @r{only some @acronym{NNTP} groups, where I want to autodetect spam}
+((spam-autodetect . t))
+
+;; @r{my nnimap @samp{nnimap+mail.lifelogs.com:spam} group}
+
+;; @r{this is a spam group}
+((spam-contents gnus-group-spam-classification-spam)
+
+ ;; @r{any spam (which happens when I enter for all unseen messages,}
+ ;; @r{because of the @code{gnus-spam-newsgroup-contents} setting above), goes to}
+ ;; @r{@samp{nnimap+mail.lifelogs.com:train} unless I mark it as ham}
+
+ (spam-process-destination "nnimap+mail.lifelogs.com:train")
+
+ ;; @r{any ham goes to my @samp{nnimap+mail.lifelogs.com:mail} folder, but}
+ ;; @r{also to my @samp{nnimap+mail.lifelogs.com:trainham} folder for training}
+
+ (ham-process-destination "nnimap+mail.lifelogs.com:mail"
+ "nnimap+mail.lifelogs.com:trainham")
+ ;; @r{in this group, only @samp{!} marks are ham}
+ (ham-marks
+ (gnus-ticked-mark))
+ ;; @r{remembers senders in the blacklist on the way out---this is}
+ ;; @r{definitely not needed, it just makes me feel better}
+ (spam-process (gnus-group-spam-exit-processor-blacklist)))
+
+;; @r{Later, on the @acronym{IMAP} server I use the @samp{train} group for training}
+;; @r{SpamAssassin to recognize spam, and the @samp{trainham} group fora}
+;; @r{recognizing ham---but Gnus has nothing to do with it.}
+
+@end example
+
+@subsubheading Using @code{spam.el} on an IMAP server with a statistical filter on the server
+From Reiner Steib <reiner.steib@@gmx.de>.
+
+My provider has set up bogofilter (in combination with @acronym{DCC}) on
+the mail server (@acronym{IMAP}). Recognized spam goes to
+@samp{spam.detected}, the rest goes through the normal filter rules,
+i.e., to @samp{some.folder} or to @samp{INBOX}. Training on false
+positives or negatives is done by copying or moving the article to
+@samp{training.ham} or @samp{training.spam} respectively. A cron job on
+the server feeds those to bogofilter with the suitable ham or spam
+options and deletes them from the @samp{training.ham} and
+@samp{training.spam} folders.
+
+With the following entries in @code{gnus-parameters}, @code{spam.el}
+does most of the job for me:
+
+@lisp
+ ("nnimap:spam\\.detected"
+ (gnus-article-sort-functions '(gnus-article-sort-by-chars))
+ (ham-process-destination "nnimap:INBOX" "nnimap:training.ham")
+ (spam-contents gnus-group-spam-classification-spam))
+ ("nnimap:\\(INBOX\\|other-folders\\)"
+ (spam-process-destination . "nnimap:training.spam")
+ (spam-contents gnus-group-spam-classification-ham))
+@end lisp
+
+@itemize
+
+@item @b{The Spam folder:}
+
+In the folder @samp{spam.detected}, I have to check for false positives
+(i.e., legitimate mails, that were wrongly judged as spam by
+bogofilter or DCC).
+
+Because of the @code{gnus-group-spam-classification-spam} entry, all
+messages are marked as spam (with @code{$}). When I find a false
+positive, I mark the message with some other ham mark
+(@code{ham-marks}, @ref{Spam and Ham Processors}). On group exit,
+those messages are copied to both groups, @samp{INBOX} (where I want
+to have the article) and @samp{training.ham} (for training bogofilter)
+and deleted from the @samp{spam.detected} folder.
+
+The @code{gnus-article-sort-by-chars} entry simplifies detection of
+false positives for me. I receive lots of worms (sweN, @dots{}), that all
+have a similar size. Grouping them by size (i.e., chars) makes finding
+other false positives easier. (Of course worms aren't @i{spam}
+(@acronym{UCE}, @acronym{UBE}) strictly speaking. Anyhow, bogofilter is
+an excellent tool for filtering those unwanted mails for me.)
+
+@item @b{Ham folders:}
+
+In my ham folders, I just hit @kbd{S x}
+(@code{gnus-summary-mark-as-spam}) whenever I see an unrecognized spam
+mail (false negative). On group exit, those messages are moved to
+@samp{training.spam}.
+@end itemize
+
+@subsubheading Reporting spam articles in Gmane groups with @code{spam-report.el}
+
+From Reiner Steib <reiner.steib@@gmx.de>.
+
+With following entry in @code{gnus-parameters}, @kbd{S x}
+(@code{gnus-summary-mark-as-spam}) marks articles in @code{gmane.*}
+groups as spam and reports the to Gmane at group exit:
+
+@lisp
+ ("^gmane\\."
+ (spam-process (gnus-group-spam-exit-processor-report-gmane)))
+@end lisp
+
+Additionally, I use @code{(setq spam-report-gmane-use-article-number nil)}
+because I don't read the groups directly from news.gmane.org, but
+through my local news server (leafnode). I.e., the article numbers are
+not the same as on news.gmane.org, thus @code{spam-report.el} has to check
+the @code{X-Report-Spam} header to find the correct number.
+
+@node Spam Back Ends
+@subsection Spam Back Ends
+@cindex spam back ends
+
+The spam package offers a variety of back ends for detecting spam.
+Each back end defines a set of methods for detecting spam
+(@pxref{Filtering Incoming Mail}, @pxref{Detecting Spam in Groups}),
+and a pair of spam and ham processors (@pxref{Spam and Ham
+Processors}).
+
+@menu
+* Blacklists and Whitelists::
+* BBDB Whitelists::
+* Gmane Spam Reporting::
+* Anti-spam Hashcash Payments::
+* Blackholes::
+* Regular Expressions Header Matching::
+* Bogofilter::
+* SpamAssassin back end::
+* ifile spam filtering::
+* Spam Statistics Filtering::
+* SpamOracle::
+@end menu
+
+@node Blacklists and Whitelists
+@subsubsection Blacklists and Whitelists
+@cindex spam filtering
+@cindex whitelists, spam filtering
+@cindex blacklists, spam filtering
+@cindex spam
+
+@defvar spam-use-blacklist
+
+Set this variable to @code{t} if you want to use blacklists when
+splitting incoming mail. Messages whose senders are in the blacklist
+will be sent to the @code{spam-split-group}. This is an explicit
+filter, meaning that it acts only on mail senders @emph{declared} to
+be spammers.
+
+@end defvar
+
+@defvar spam-use-whitelist
+
+Set this variable to @code{t} if you want to use whitelists when
+splitting incoming mail. Messages whose senders are not in the
+whitelist will be sent to the next spam-split rule. This is an
+explicit filter, meaning that unless someone is in the whitelist, their
+messages are not assumed to be spam or ham.
+
+@end defvar
+
+@defvar spam-use-whitelist-exclusive
+
+Set this variable to @code{t} if you want to use whitelists as an
+implicit filter, meaning that every message will be considered spam
+unless the sender is in the whitelist. Use with care.
+
+@end defvar
+
+@defvar gnus-group-spam-exit-processor-blacklist
+
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the senders of
+spam-marked articles will be added to the blacklist.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-spam-exit-processor-blacklist}, it is recommended
+that you use @code{(spam spam-use-blacklist)}. Everything will work
+the same way, we promise.
+
+@end defvar
+
+@defvar gnus-group-ham-exit-processor-whitelist
+
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the senders of
+ham-marked articles in @emph{ham} groups will be added to the
+whitelist.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-ham-exit-processor-whitelist}, it is recommended
+that you use @code{(ham spam-use-whitelist)}. Everything will work
+the same way, we promise.
+
+@end defvar
+
+Blacklists are lists of regular expressions matching addresses you
+consider to be spam senders. For instance, to block mail from any
+sender at @samp{vmadmin.com}, you can put @samp{vmadmin.com} in your
+blacklist. You start out with an empty blacklist. Blacklist entries
+use the Emacs regular expression syntax.
+
+Conversely, whitelists tell Gnus what addresses are considered
+legitimate. All messages from whitelisted addresses are considered
+non-spam. Also see @ref{BBDB Whitelists}. Whitelist entries use the
+Emacs regular expression syntax.
+
+The blacklist and whitelist file locations can be customized with the
+@code{spam-directory} variable (@file{~/News/spam} by default), or
+the @code{spam-whitelist} and @code{spam-blacklist} variables
+directly. The whitelist and blacklist files will by default be in the
+@code{spam-directory} directory, named @file{whitelist} and
+@file{blacklist} respectively.
+
+@node BBDB Whitelists
+@subsubsection BBDB Whitelists
+@cindex spam filtering
+@cindex BBDB whitelists, spam filtering
+@cindex BBDB, spam filtering
+@cindex spam
+
+@defvar spam-use-BBDB
+
+Analogous to @code{spam-use-whitelist} (@pxref{Blacklists and
+Whitelists}), but uses the BBDB as the source of whitelisted
+addresses, without regular expressions. You must have the BBDB loaded
+for @code{spam-use-BBDB} to work properly. Messages whose senders are
+not in the BBDB will be sent to the next spam-split rule. This is an
+explicit filter, meaning that unless someone is in the BBDB, their
+messages are not assumed to be spam or ham.
+
+@end defvar
+
+@defvar spam-use-BBDB-exclusive
+
+Set this variable to @code{t} if you want to use the BBDB as an
+implicit filter, meaning that every message will be considered spam
+unless the sender is in the BBDB@. Use with care. Only sender
+addresses in the BBDB will be allowed through; all others will be
+classified as spammers.
+
+While @code{spam-use-BBDB-exclusive} @emph{can} be used as an alias
+for @code{spam-use-BBDB} as far as @code{spam.el} is concerned, it is
+@emph{not} a separate back end. If you set
+@code{spam-use-BBDB-exclusive} to @code{t}, @emph{all} your BBDB splitting
+will be exclusive.
+
+@end defvar
+
+@defvar gnus-group-ham-exit-processor-BBDB
+
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the senders of
+ham-marked articles in @emph{ham} groups will be added to the
+BBDB.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-ham-exit-processor-BBDB}, it is recommended
+that you use @code{(ham spam-use-BBDB)}. Everything will work
+the same way, we promise.
+
+@end defvar
+
+@node Gmane Spam Reporting
+@subsubsection Gmane Spam Reporting
+@cindex spam reporting
+@cindex Gmane, spam reporting
+@cindex Gmane, spam reporting
+@cindex spam
+
+@defvar gnus-group-spam-exit-processor-report-gmane
+
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the spam-marked
+articles groups will be reported to the Gmane administrators via a
+HTTP request.
+
+Gmane can be found at @uref{http://gmane.org}.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-spam-exit-processor-report-gmane}, it is recommended
+that you use @code{(spam spam-use-gmane)}. Everything will work the
+same way, we promise.
+
+@end defvar
+
+@defvar spam-report-gmane-use-article-number
+
+This variable is @code{t} by default. Set it to @code{nil} if you are
+running your own news server, for instance, and the local article
+numbers don't correspond to the Gmane article numbers. When
+@code{spam-report-gmane-use-article-number} is @code{nil},
+@code{spam-report.el} will fetch the number from the article headers.
+
+@end defvar
+
+@defvar spam-report-user-mail-address
+
+Mail address exposed in the User-Agent spam reports to Gmane. It allows
+the Gmane administrators to contact you in case of misreports. The
+default is @code{user-mail-address}.
+
+@end defvar
+
+@node Anti-spam Hashcash Payments
+@subsubsection Anti-spam Hashcash Payments
+@cindex spam filtering
+@cindex hashcash, spam filtering
+@cindex spam
+
+@defvar spam-use-hashcash
+
+Similar to @code{spam-use-whitelist} (@pxref{Blacklists and
+Whitelists}), but uses hashcash tokens for whitelisting messages
+instead of the sender address. Messages without a hashcash payment
+token will be sent to the next spam-split rule. This is an explicit
+filter, meaning that unless a hashcash token is found, the messages
+are not assumed to be spam or ham.
+
+@end defvar
+
+@node Blackholes
+@subsubsection Blackholes
+@cindex spam filtering
+@cindex blackholes, spam filtering
+@cindex spam
+
+@defvar spam-use-blackholes
+
+This option is disabled by default. You can let Gnus consult the
+blackhole-type distributed spam processing systems (DCC, for instance)
+when you set this option. The variable @code{spam-blackhole-servers}
+holds the list of blackhole servers Gnus will consult. The current
+list is fairly comprehensive, but make sure to let us know if it
+contains outdated servers.
+
+The blackhole check uses the @code{dig.el} package, but you can tell
+@code{spam.el} to use @code{dns.el} instead for better performance if
+you set @code{spam-use-dig} to @code{nil}. It is not recommended at
+this time to set @code{spam-use-dig} to @code{nil} despite the
+possible performance improvements, because some users may be unable to
+use it, but you can try it and see if it works for you.
+
+@end defvar
+
+@defvar spam-blackhole-servers
+
+The list of servers to consult for blackhole checks.
+
+@end defvar
+
+@defvar spam-blackhole-good-server-regex
+
+A regular expression for IPs that should not be checked against the
+blackhole server list. When set to @code{nil}, it has no effect.
+
+@end defvar
+
+@defvar spam-use-dig
+
+Use the @code{dig.el} package instead of the @code{dns.el} package.
+The default setting of @code{t} is recommended.
+
+@end defvar
+
+Blackhole checks are done only on incoming mail. There is no spam or
+ham processor for blackholes.
+
+@node Regular Expressions Header Matching
+@subsubsection Regular Expressions Header Matching
+@cindex spam filtering
+@cindex regular expressions header matching, spam filtering
+@cindex spam
+
+@defvar spam-use-regex-headers
+
+This option is disabled by default. You can let Gnus check the
+message headers against lists of regular expressions when you set this
+option. The variables @code{spam-regex-headers-spam} and
+@code{spam-regex-headers-ham} hold the list of regular expressions.
+Gnus will check against the message headers to determine if the
+message is spam or ham, respectively.
+
+@end defvar
+
+@defvar spam-regex-headers-spam
+
+The list of regular expressions that, when matched in the headers of
+the message, positively identify it as spam.
+
+@end defvar
+
+@defvar spam-regex-headers-ham
+
+The list of regular expressions that, when matched in the headers of
+the message, positively identify it as ham.
+
+@end defvar
+
+Regular expression header checks are done only on incoming mail.
+There is no specific spam or ham processor for regular expressions.
+
+@node Bogofilter
+@subsubsection Bogofilter
+@cindex spam filtering
+@cindex bogofilter, spam filtering
+@cindex spam
+
+@defvar spam-use-bogofilter
+
+Set this variable if you want @code{spam-split} to use Eric Raymond's
+speedy Bogofilter.
+
+With a minimum of care for associating the @samp{$} mark for spam
+articles only, Bogofilter training all gets fairly automatic. You
+should do this until you get a few hundreds of articles in each
+category, spam or not. The command @kbd{S t} in summary mode, either
+for debugging or for curiosity, shows the @emph{spamicity} score of
+the current article (between 0.0 and 1.0).
+
+Bogofilter determines if a message is spam based on a specific
+threshold. That threshold can be customized, consult the Bogofilter
+documentation.
+
+If the @code{bogofilter} executable is not in your path, Bogofilter
+processing will be turned off.
+
+You should not enable this if you use @code{spam-use-bogofilter-headers}.
+
+@end defvar
+
+@table @kbd
+@item M s t
+@itemx S t
+@kindex M s t
+@kindex S t
+@findex spam-bogofilter-score
+Get the Bogofilter spamicity score (@code{spam-bogofilter-score}).
+@end table
+
+@defvar spam-use-bogofilter-headers
+
+Set this variable if you want @code{spam-split} to use Eric Raymond's
+speedy Bogofilter, looking only at the message headers. It works
+similarly to @code{spam-use-bogofilter}, but the @code{X-Bogosity} header
+must be in the message already. Normally you would do this with a
+procmail recipe or something similar; consult the Bogofilter
+installation documents for details.
+
+You should not enable this if you use @code{spam-use-bogofilter}.
+
+@end defvar
+
+@defvar gnus-group-spam-exit-processor-bogofilter
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, spam-marked articles
+will be added to the Bogofilter spam database.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-spam-exit-processor-bogofilter}, it is recommended
+that you use @code{(spam spam-use-bogofilter)}. Everything will work
+the same way, we promise.
+@end defvar
+
+@defvar gnus-group-ham-exit-processor-bogofilter
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the ham-marked
+articles in @emph{ham} groups will be added to the Bogofilter database
+of non-spam messages.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-ham-exit-processor-bogofilter}, it is recommended
+that you use @code{(ham spam-use-bogofilter)}. Everything will work
+the same way, we promise.
+@end defvar
+
+@defvar spam-bogofilter-database-directory
+
+This is the directory where Bogofilter will store its databases. It
+is not specified by default, so Bogofilter will use its own default
+database directory.
+
+@end defvar
+
+The Bogofilter mail classifier is similar to @command{ifile} in intent and
+purpose. A ham and a spam processor are provided, plus the
+@code{spam-use-bogofilter} and @code{spam-use-bogofilter-headers}
+variables to indicate to spam-split that Bogofilter should either be
+used, or has already been used on the article. The 0.9.2.1 version of
+Bogofilter was used to test this functionality.
+
+@node SpamAssassin back end
+@subsubsection SpamAssassin back end
+@cindex spam filtering
+@cindex spamassassin, spam filtering
+@cindex spam
+
+@defvar spam-use-spamassassin
+
+Set this variable if you want @code{spam-split} to use SpamAssassin.
+
+SpamAssassin assigns a score to each article based on a set of rules
+and tests, including a Bayesian filter. The Bayesian filter can be
+trained by associating the @samp{$} mark for spam articles. The
+spam score can be viewed by using the command @kbd{S t} in summary
+mode.
+
+If you set this variable, each article will be processed by
+SpamAssassin when @code{spam-split} is called. If your mail is
+preprocessed by SpamAssassin, and you want to just use the
+SpamAssassin headers, set @code{spam-use-spamassassin-headers}
+instead.
+
+You should not enable this if you use
+@code{spam-use-spamassassin-headers}.
+
+@end defvar
+
+@defvar spam-use-spamassassin-headers
+
+Set this variable if your mail is preprocessed by SpamAssassin and
+want @code{spam-split} to split based on the SpamAssassin headers.
+
+You should not enable this if you use @code{spam-use-spamassassin}.
+
+@end defvar
+
+@defvar spam-spamassassin-program
+
+This variable points to the SpamAssassin executable. If you have
+@code{spamd} running, you can set this variable to the @code{spamc}
+executable for faster processing. See the SpamAssassin documentation
+for more information on @code{spamd}/@code{spamc}.
+
+@end defvar
+
+SpamAssassin is a powerful and flexible spam filter that uses a wide
+variety of tests to identify spam. A ham and a spam processors are
+provided, plus the @code{spam-use-spamassassin} and
+@code{spam-use-spamassassin-headers} variables to indicate to
+spam-split that SpamAssassin should be either used, or has already
+been used on the article. The 2.63 version of SpamAssassin was used
+to test this functionality.
+
+@node ifile spam filtering
+@subsubsection ifile spam filtering
+@cindex spam filtering
+@cindex ifile, spam filtering
+@cindex spam
+
+@defvar spam-use-ifile
+
+Enable this variable if you want @code{spam-split} to use @command{ifile}, a
+statistical analyzer similar to Bogofilter.
+
+@end defvar
+
+@defvar spam-ifile-all-categories
+
+Enable this variable if you want @code{spam-use-ifile} to give you all
+the ifile categories, not just spam/non-spam. If you use this, make
+sure you train ifile as described in its documentation.
+
+@end defvar
+
+@defvar spam-ifile-spam-category
+
+This is the category of spam messages as far as ifile is concerned.
+The actual string used is irrelevant, but you probably want to leave
+the default value of @samp{spam}.
+@end defvar
+
+@defvar spam-ifile-database
+
+This is the filename for the ifile database. It is not specified by
+default, so ifile will use its own default database name.
+
+@end defvar
+
+The ifile mail classifier is similar to Bogofilter in intent and
+purpose. A ham and a spam processor are provided, plus the
+@code{spam-use-ifile} variable to indicate to spam-split that ifile
+should be used. The 1.2.1 version of ifile was used to test this
+functionality.
+
+@node Spam Statistics Filtering
+@subsubsection Spam Statistics Filtering
+@cindex spam filtering
+@cindex spam-stat, spam filtering
+@cindex spam-stat
+@cindex spam
+
+This back end uses the Spam Statistics Emacs Lisp package to perform
+statistics-based filtering (@pxref{Spam Statistics Package}). Before
+using this, you may want to perform some additional steps to
+initialize your Spam Statistics dictionary. @xref{Creating a
+spam-stat dictionary}.
+
+@defvar spam-use-stat
+
+@end defvar
+
+@defvar gnus-group-spam-exit-processor-stat
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the spam-marked
+articles will be added to the spam-stat database of spam messages.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-spam-exit-processor-stat}, it is recommended
+that you use @code{(spam spam-use-stat)}. Everything will work
+the same way, we promise.
+@end defvar
+
+@defvar gnus-group-ham-exit-processor-stat
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameters or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is
+added to a group's @code{spam-process} parameter, the ham-marked
+articles in @emph{ham} groups will be added to the spam-stat database
+of non-spam messages.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-ham-exit-processor-stat}, it is recommended
+that you use @code{(ham spam-use-stat)}. Everything will work
+the same way, we promise.
+@end defvar
+
+This enables @code{spam.el} to cooperate with @file{spam-stat.el}.
+@file{spam-stat.el} provides an internal (Lisp-only) spam database,
+which unlike ifile or Bogofilter does not require external programs.
+A spam and a ham processor, and the @code{spam-use-stat} variable for
+@code{spam-split} are provided.
+
+@node SpamOracle
+@subsubsection Using SpamOracle with Gnus
+@cindex spam filtering
+@cindex SpamOracle
+@cindex spam
+
+An easy way to filter out spam is to use SpamOracle. SpamOracle is an
+statistical mail filtering tool written by Xavier Leroy and needs to be
+installed separately.
+
+There are several ways to use SpamOracle with Gnus. In all cases, your
+mail is piped through SpamOracle in its @emph{mark} mode. SpamOracle will
+then enter an @samp{X-Spam} header indicating whether it regards the
+mail as a spam mail or not.
+
+One possibility is to run SpamOracle as a @code{:prescript} from the
+@xref{Mail Source Specifiers}, (@pxref{SpamAssassin}). This method has
+the advantage that the user can see the @emph{X-Spam} headers.
+
+The easiest method is to make @file{spam.el} (@pxref{Spam Package})
+call SpamOracle.
+
+@vindex spam-use-spamoracle
+To enable SpamOracle usage by @code{spam.el}, set the variable
+@code{spam-use-spamoracle} to @code{t} and configure the
+@code{nnmail-split-fancy} or @code{nnimap-split-fancy}. @xref{Spam
+Package}. In this example the @samp{INBOX} of an nnimap server is
+filtered using SpamOracle. Mails recognized as spam mails will be
+moved to @code{spam-split-group}, @samp{Junk} in this case. Ham
+messages stay in @samp{INBOX}:
+
+@example
+(setq spam-use-spamoracle t
+ spam-split-group "Junk"
+ ;; @r{for nnimap you'll probably want to set nnimap-split-methods, see the manual}
+ nnimap-split-inbox '("INBOX")
+ nnimap-split-fancy '(| (: spam-split) "INBOX"))
+@end example
+
+@defvar spam-use-spamoracle
+Set to @code{t} if you want Gnus to enable spam filtering using
+SpamOracle.
+@end defvar
+
+@defvar spam-spamoracle-binary
+Gnus uses the SpamOracle binary called @file{spamoracle} found in the
+user's PATH@. Using the variable @code{spam-spamoracle-binary}, this
+can be customized.
+@end defvar
+
+@defvar spam-spamoracle-database
+By default, SpamOracle uses the file @file{~/.spamoracle.db} as a database to
+store its analysis. This is controlled by the variable
+@code{spam-spamoracle-database} which defaults to @code{nil}. That means
+the default SpamOracle database will be used. In case you want your
+database to live somewhere special, set
+@code{spam-spamoracle-database} to this path.
+@end defvar
+
+SpamOracle employs a statistical algorithm to determine whether a
+message is spam or ham. In order to get good results, meaning few
+false hits or misses, SpamOracle needs training. SpamOracle learns
+the characteristics of your spam mails. Using the @emph{add} mode
+(training mode) one has to feed good (ham) and spam mails to
+SpamOracle. This can be done by pressing @kbd{|} in the Summary
+buffer and pipe the mail to a SpamOracle process or using
+@file{spam.el}'s spam- and ham-processors, which is much more
+convenient. For a detailed description of spam- and ham-processors,
+@xref{Spam Package}.
+
+@defvar gnus-group-spam-exit-processor-spamoracle
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameter or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is added
+to a group's @code{spam-process} parameter, spam-marked articles will be
+sent to SpamOracle as spam samples.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-spam-exit-processor-spamoracle}, it is recommended
+that you use @code{(spam spam-use-spamoracle)}. Everything will work
+the same way, we promise.
+@end defvar
+
+@defvar gnus-group-ham-exit-processor-spamoracle
+Add this symbol to a group's @code{spam-process} parameter by
+customizing the group parameter or the
+@code{gnus-spam-process-newsgroups} variable. When this symbol is added
+to a group's @code{spam-process} parameter, the ham-marked articles in
+@emph{ham} groups will be sent to the SpamOracle as samples of ham
+messages.
+
+@emph{WARNING}
+
+Instead of the obsolete
+@code{gnus-group-ham-exit-processor-spamoracle}, it is recommended
+that you use @code{(ham spam-use-spamoracle)}. Everything will work
+the same way, we promise.
+@end defvar
+
+@emph{Example:} These are the Group Parameters of a group that has been
+classified as a ham group, meaning that it should only contain ham
+messages.
+@example
+ ((spam-contents gnus-group-spam-classification-ham)
+ (spam-process ((ham spam-use-spamoracle)
+ (spam spam-use-spamoracle))))
+@end example
+For this group the @code{spam-use-spamoracle} is installed for both
+ham and spam processing. If the group contains spam message
+(e.g., because SpamOracle has not had enough sample messages yet) and
+the user marks some messages as spam messages, these messages will be
+processed by SpamOracle. The processor sends the messages to
+SpamOracle as new samples for spam.
+
+@node Extending the Spam package
+@subsection Extending the Spam package
+@cindex spam filtering
+@cindex spam elisp package, extending
+@cindex extending the spam elisp package
+
+Say you want to add a new back end called blackbox. For filtering
+incoming mail, provide the following:
+
+@enumerate
+
+@item
+Code
+
+@lisp
+(defvar spam-use-blackbox nil
+ "True if blackbox should be used.")
+@end lisp
+
+Write @code{spam-check-blackbox} if Blackbox can check incoming mail.
+
+Write @code{spam-blackbox-register-routine} and
+@code{spam-blackbox-unregister-routine} using the bogofilter
+register/unregister routines as a start, or other register/unregister
+routines more appropriate to Blackbox, if Blackbox can
+register/unregister spam and ham.
+
+@item
+Functionality
+
+The @code{spam-check-blackbox} function should return @samp{nil} or
+@code{spam-split-group}, observing the other conventions. See the
+existing @code{spam-check-*} functions for examples of what you can
+do, and stick to the template unless you fully understand the reasons
+why you aren't.
+
+@end enumerate
+
+For processing spam and ham messages, provide the following:
+
+@enumerate
+
+@item
+Code
+
+Note you don't have to provide a spam or a ham processor. Only
+provide them if Blackbox supports spam or ham processing.
+
+Also, ham and spam processors are being phased out as single
+variables. Instead the form @code{(spam spam-use-blackbox)} or
+@code{(ham spam-use-blackbox)} is favored. For now, spam/ham
+processor variables are still around but they won't be for long.
+
+@lisp
+(defvar gnus-group-spam-exit-processor-blackbox "blackbox-spam"
+ "The Blackbox summary exit spam processor.
+Only applicable to spam groups.")
+
+(defvar gnus-group-ham-exit-processor-blackbox "blackbox-ham"
+ "The whitelist summary exit ham processor.
+Only applicable to non-spam (unclassified and ham) groups.")
+
+@end lisp
+
+@item
+Gnus parameters
+
+Add
+@lisp
+(const :tag "Spam: Blackbox" (spam spam-use-blackbox))
+(const :tag "Ham: Blackbox" (ham spam-use-blackbox))
+@end lisp
+to the @code{spam-process} group parameter in @code{gnus.el}. Make
+sure you do it twice, once for the parameter and once for the
+variable customization.
+
+Add
+@lisp
+(variable-item spam-use-blackbox)
+@end lisp
+to the @code{spam-autodetect-methods} group parameter in
+@code{gnus.el} if Blackbox can check incoming mail for spam contents.
+
+Finally, use the appropriate @code{spam-install-*-backend} function in
+@code{spam.el}. Here are the available functions.
+
+
+@enumerate
+
+@item
+@code{spam-install-backend-alias}
+
+This function will simply install an alias for a back end that does
+everything like the original back end. It is currently only used to
+make @code{spam-use-BBDB-exclusive} act like @code{spam-use-BBDB}.
+
+@item
+@code{spam-install-nocheck-backend}
+
+This function installs a back end that has no check function, but can
+register/unregister ham or spam. The @code{spam-use-gmane} back end is
+such a back end.
+
+@item
+@code{spam-install-checkonly-backend}
+
+This function will install a back end that can only check incoming mail
+for spam contents. It can't register or unregister messages.
+@code{spam-use-blackholes} and @code{spam-use-hashcash} are such
+back ends.
+
+@item
+@code{spam-install-statistical-checkonly-backend}
+
+This function installs a statistical back end (one which requires the
+full body of a message to check it) that can only check incoming mail
+for contents. @code{spam-use-regex-body} is such a filter.
+
+@item
+@code{spam-install-statistical-backend}
+
+This function install a statistical back end with incoming checks and
+registration/unregistration routines. @code{spam-use-bogofilter} is
+set up this way.
+
+@item
+@code{spam-install-backend}
+
+This is the most normal back end installation, where a back end that can
+check and register/unregister messages is set up without statistical
+abilities. The @code{spam-use-BBDB} is such a back end.
+
+@item
+@code{spam-install-mover-backend}
+
+Mover back ends are internal to @code{spam.el} and specifically move
+articles around when the summary is exited. You will very probably
+never install such a back end.
+@end enumerate
+
+@end enumerate
+
+@node Spam Statistics Package
+@subsection Spam Statistics Package
+@cindex Paul Graham
+@cindex Graham, Paul
+@cindex naive Bayesian spam filtering
+@cindex Bayesian spam filtering, naive
+@cindex spam filtering, naive Bayesian
+
+Paul Graham has written an excellent essay about spam filtering using
+statistics: @uref{http://www.paulgraham.com/spam.html,A Plan for
+Spam}. In it he describes the inherent deficiency of rule-based
+filtering as used by SpamAssassin, for example: Somebody has to write
+the rules, and everybody else has to install these rules. You are
+always late. It would be much better, he argues, to filter mail based
+on whether it somehow resembles spam or non-spam. One way to measure
+this is word distribution. He then goes on to describe a solution
+that checks whether a new mail resembles any of your other spam mails
+or not.
+
+The basic idea is this: Create a two collections of your mail, one
+with spam, one with non-spam. Count how often each word appears in
+either collection, weight this by the total number of mails in the
+collections, and store this information in a dictionary. For every
+word in a new mail, determine its probability to belong to a spam or a
+non-spam mail. Use the 15 most conspicuous words, compute the total
+probability of the mail being spam. If this probability is higher
+than a certain threshold, the mail is considered to be spam.
+
+The Spam Statistics package adds support to Gnus for this kind of
+filtering. It can be used as one of the back ends of the Spam package
+(@pxref{Spam Package}), or by itself.
+
+Before using the Spam Statistics package, you need to set it up.
+First, you need two collections of your mail, one with spam, one with
+non-spam. Then you need to create a dictionary using these two
+collections, and save it. And last but not least, you need to use
+this dictionary in your fancy mail splitting rules.
+
+@menu
+* Creating a spam-stat dictionary::
+* Splitting mail using spam-stat::
+* Low-level interface to the spam-stat dictionary::
+@end menu
+
+@node Creating a spam-stat dictionary
+@subsubsection Creating a spam-stat dictionary
+
+Before you can begin to filter spam based on statistics, you must
+create these statistics based on two mail collections, one with spam,
+one with non-spam. These statistics are then stored in a dictionary
+for later use. In order for these statistics to be meaningful, you
+need several hundred emails in both collections.
+
+Gnus currently supports only the nnml back end for automated dictionary
+creation. The nnml back end stores all mails in a directory, one file
+per mail. Use the following:
+
+@defun spam-stat-process-spam-directory
+Create spam statistics for every file in this directory. Every file
+is treated as one spam mail.
+@end defun
+
+@defun spam-stat-process-non-spam-directory
+Create non-spam statistics for every file in this directory. Every
+file is treated as one non-spam mail.
+@end defun
+
+Usually you would call @code{spam-stat-process-spam-directory} on a
+directory such as @file{~/Mail/mail/spam} (this usually corresponds to
+the group @samp{nnml:mail.spam}), and you would call
+@code{spam-stat-process-non-spam-directory} on a directory such as
+@file{~/Mail/mail/misc} (this usually corresponds to the group
+@samp{nnml:mail.misc}).
+
+When you are using @acronym{IMAP}, you won't have the mails available
+locally, so that will not work. One solution is to use the Gnus Agent
+to cache the articles. Then you can use directories such as
+@file{"~/News/agent/nnimap/mail.yourisp.com/personal_spam"} for
+@code{spam-stat-process-spam-directory}. @xref{Agent as Cache}.
+
+@defvar spam-stat
+This variable holds the hash-table with all the statistics---the
+dictionary we have been talking about. For every word in either
+collection, this hash-table stores a vector describing how often the
+word appeared in spam and often it appeared in non-spam mails.
+@end defvar
+
+If you want to regenerate the statistics from scratch, you need to
+reset the dictionary.
+
+@defun spam-stat-reset
+Reset the @code{spam-stat} hash-table, deleting all the statistics.
+@end defun
+
+When you are done, you must save the dictionary. The dictionary may
+be rather large. If you will not update the dictionary incrementally
+(instead, you will recreate it once a month, for example), then you
+can reduce the size of the dictionary by deleting all words that did
+not appear often enough or that do not clearly belong to only spam or
+only non-spam mails.
+
+@defun spam-stat-reduce-size
+Reduce the size of the dictionary. Use this only if you do not want
+to update the dictionary incrementally.
+@end defun
+
+@defun spam-stat-save
+Save the dictionary.
+@end defun
+
+@defvar spam-stat-file
+The filename used to store the dictionary. This defaults to
+@file{~/.spam-stat.el}.
+@end defvar
+
+@node Splitting mail using spam-stat
+@subsubsection Splitting mail using spam-stat
+
+This section describes how to use the Spam statistics
+@emph{independently} of the @xref{Spam Package}.
+
+First, add the following to your @file{~/.gnus.el} file:
+
+@lisp
+(require 'spam-stat)
+(spam-stat-load)
+@end lisp
+
+This will load the necessary Gnus code, and the dictionary you
+created.
+
+Next, you need to adapt your fancy splitting rules: You need to
+determine how to use @code{spam-stat}. The following examples are for
+the nnml back end. Using the nnimap back end works just as well. Just
+use @code{nnimap-split-fancy} instead of @code{nnmail-split-fancy}.
+
+In the simplest case, you only have two groups, @samp{mail.misc} and
+@samp{mail.spam}. The following expression says that mail is either
+spam or it should go into @samp{mail.misc}. If it is spam, then
+@code{spam-stat-split-fancy} will return @samp{mail.spam}.
+
+@lisp
+(setq nnmail-split-fancy
+ `(| (: spam-stat-split-fancy)
+ "mail.misc"))
+@end lisp
+
+@defvar spam-stat-split-fancy-spam-group
+The group to use for spam. Default is @samp{mail.spam}.
+@end defvar
+
+If you also filter mail with specific subjects into other groups, use
+the following expression. Only mails not matching the regular
+expression are considered potential spam.
+
+@lisp
+(setq nnmail-split-fancy
+ `(| ("Subject" "\\bspam-stat\\b" "mail.emacs")
+ (: spam-stat-split-fancy)
+ "mail.misc"))
+@end lisp
+
+If you want to filter for spam first, then you must be careful when
+creating the dictionary. Note that @code{spam-stat-split-fancy} must
+consider both mails in @samp{mail.emacs} and in @samp{mail.misc} as
+non-spam, therefore both should be in your collection of non-spam
+mails, when creating the dictionary!
+
+@lisp
+(setq nnmail-split-fancy
+ `(| (: spam-stat-split-fancy)
+ ("Subject" "\\bspam-stat\\b" "mail.emacs")
+ "mail.misc"))
+@end lisp
+
+You can combine this with traditional filtering. Here, we move all
+HTML-only mails into the @samp{mail.spam.filtered} group. Note that since
+@code{spam-stat-split-fancy} will never see them, the mails in
+@samp{mail.spam.filtered} should be neither in your collection of spam mails,
+nor in your collection of non-spam mails, when creating the
+dictionary!
+
+@lisp
+(setq nnmail-split-fancy
+ `(| ("Content-Type" "text/html" "mail.spam.filtered")
+ (: spam-stat-split-fancy)
+ ("Subject" "\\bspam-stat\\b" "mail.emacs")
+ "mail.misc"))
+@end lisp
+
+
+@node Low-level interface to the spam-stat dictionary
+@subsubsection Low-level interface to the spam-stat dictionary
+
+The main interface to using @code{spam-stat}, are the following functions:
+
+@defun spam-stat-buffer-is-spam
+Called in a buffer, that buffer is considered to be a new spam mail.
+Use this for new mail that has not been processed before.
+@end defun
+
+@defun spam-stat-buffer-is-no-spam
+Called in a buffer, that buffer is considered to be a new non-spam
+mail. Use this for new mail that has not been processed before.
+@end defun
+
+@defun spam-stat-buffer-change-to-spam
+Called in a buffer, that buffer is no longer considered to be normal
+mail but spam. Use this to change the status of a mail that has
+already been processed as non-spam.
+@end defun
+
+@defun spam-stat-buffer-change-to-non-spam
+Called in a buffer, that buffer is no longer considered to be spam but
+normal mail. Use this to change the status of a mail that has already
+been processed as spam.
+@end defun
+
+@defun spam-stat-save
+Save the hash table to the file. The filename used is stored in the
+variable @code{spam-stat-file}.
+@end defun
+
+@defun spam-stat-load
+Load the hash table from a file. The filename used is stored in the
+variable @code{spam-stat-file}.
+@end defun
+
+@defun spam-stat-score-word
+Return the spam score for a word.
+@end defun
+
+@defun spam-stat-score-buffer
+Return the spam score for a buffer.
+@end defun
+
+@defun spam-stat-split-fancy
+Use this function for fancy mail splitting. Add the rule @samp{(:
+spam-stat-split-fancy)} to @code{nnmail-split-fancy}
+@end defun
+
+Make sure you load the dictionary before using it. This requires the
+following in your @file{~/.gnus.el} file:
+
+@lisp
+(require 'spam-stat)
+(spam-stat-load)
+@end lisp
+
+Typical test will involve calls to the following functions:
+
+@smallexample
+Reset: (setq spam-stat (make-hash-table :test 'equal))
+Learn spam: (spam-stat-process-spam-directory "~/Mail/mail/spam")
+Learn non-spam: (spam-stat-process-non-spam-directory "~/Mail/mail/misc")
+Save table: (spam-stat-save)
+File size: (nth 7 (file-attributes spam-stat-file))
+Number of words: (hash-table-count spam-stat)
+Test spam: (spam-stat-test-directory "~/Mail/mail/spam")
+Test non-spam: (spam-stat-test-directory "~/Mail/mail/misc")
+Reduce table size: (spam-stat-reduce-size)
+Save table: (spam-stat-save)
+File size: (nth 7 (file-attributes spam-stat-file))
+Number of words: (hash-table-count spam-stat)
+Test spam: (spam-stat-test-directory "~/Mail/mail/spam")
+Test non-spam: (spam-stat-test-directory "~/Mail/mail/misc")
+@end smallexample
+
+Here is how you would create your dictionary:
+
+@smallexample
+Reset: (setq spam-stat (make-hash-table :test 'equal))
+Learn spam: (spam-stat-process-spam-directory "~/Mail/mail/spam")
+Learn non-spam: (spam-stat-process-non-spam-directory "~/Mail/mail/misc")
+Repeat for any other non-spam group you need...
+Reduce table size: (spam-stat-reduce-size)
+Save table: (spam-stat-save)
+@end smallexample
+
+@node The Gnus Registry
+@section The Gnus Registry
+@cindex registry
+@cindex split
+@cindex track
+
+The Gnus registry is a package that tracks messages by their
+Message-ID across all backends. This allows Gnus users to do several
+cool things, be the envy of the locals, get free haircuts, and be
+experts on world issues. Well, maybe not all of those, but the
+features are pretty cool.
+
+Although they will be explained in detail shortly, here's a quick list
+of said features in case your attention span is... never mind.
+
+@enumerate
+@item
+Split messages to their parent
+
+This keeps discussions in the same group. You can use the subject and
+the sender in addition to the Message-ID@. Several strategies are
+available.
+
+@item
+Refer to messages by ID
+
+Commands like @code{gnus-summary-refer-parent-article} can take
+advantage of the registry to jump to the referred article, regardless
+of the group the message is in.
+
+@item
+Store custom flags and keywords
+
+The registry can store custom flags and keywords for a message. For
+instance, you can mark a message ``To-Do'' this way and the flag will
+persist whether the message is in the nnimap, nnml, nnmaildir,
+etc.@: backends.
+
+@item
+Store arbitrary data
+
+Through a simple ELisp API, the registry can remember any data for a
+message. A built-in inverse map, when activated, allows quick lookups
+of all messages matching a particular set of criteria.
+@end enumerate
+
+@menu
+* Gnus Registry Setup::
+* Registry Article Refer Method::
+* Fancy splitting to parent::
+* Store custom flags and keywords::
+* Store arbitrary data::
+@end menu
+
+@node Gnus Registry Setup
+@subsection Gnus Registry Setup
+
+Fortunately, setting up the Gnus registry is pretty easy:
+
+@lisp
+(setq gnus-registry-max-entries 2500)
+
+(gnus-registry-initialize)
+@end lisp
+
+This adds registry saves to Gnus newsrc saves (which happen on exit
+and when you press @kbd{s} from the @file{*Group*} buffer. It also
+adds registry calls to article actions in Gnus (copy, move, etc.)@: so
+it's not easy to undo the initialization. See
+@code{gnus-registry-initialize} for the gory details.
+
+Here are other settings used by the author of the registry (understand
+what they do before you copy them blindly).
+
+@lisp
+(setq
+ gnus-registry-split-strategy 'majority
+ gnus-registry-ignored-groups '(("nntp" t)
+ ("nnrss" t)
+ ("spam" t)
+ ("train" t))
+ gnus-registry-max-entries 500000
+ ;; this is the default
+ gnus-registry-track-extra '(sender subject))
+@end lisp
+
+They say: keep a lot of messages around, track messages by sender and
+subject (not just parent Message-ID), and when the registry splits
+incoming mail, use a majority rule to decide where messages should go
+if there's more than one possibility. In addition, the registry
+should ignore messages in groups that match ``nntp'', ``nnrss'',
+``spam'', or ``train.''
+
+You are doubtless impressed by all this, but you ask: ``I am a Gnus
+user, I customize to live. Give me more.'' Here you go, these are
+the general settings.
+
+@defvar gnus-registry-unfollowed-groups
+The groups that will not be followed by
+@code{gnus-registry-split-fancy-with-parent}. They will still be
+remembered by the registry. This is a list of regular expressions.
+By default any group name that ends with ``delayed'', ``drafts'',
+``queue'', or ``INBOX'', belongs to the nnmairix backend, or contains
+the word ``archive'' is not followed.
+@end defvar
+
+@defvar gnus-registry-max-entries
+The number (an integer or @code{nil} for unlimited) of entries the
+registry will keep. If the registry has reached or exceeded this
+size, it will reject insertion of new entries.
+@end defvar
+
+@defvar gnus-registry-prune-factor
+This option (a float between 0 and 1) controls how much the registry
+is cut back during pruning. In order to prevent constant pruning, the
+registry will be pruned back to less than
+@code{gnus-registry-max-entries}. This option controls exactly how
+much less: the target is calculated as the maximum number of entries
+minus the maximum number times this factor. The default is 0.1:
+i.e., if your registry is limited to 50000 entries, pruning will try to
+cut back to 45000 entries. Entries with keys marked as precious will
+not be pruned.
+@end defvar
+
+@defvar gnus-registry-default-sort-function
+This option specifies how registry entries are sorted during pruning.
+If a function is given, it should sort least valuable entries first,
+as pruning starts from the beginning of the list. The default value
+is @code{gnus-registry-sort-by-creation-time}, which proposes the
+oldest entries for pruning. Set to nil to perform no sorting, which
+will speed up the pruning process.
+@end defvar
+
+@defvar gnus-registry-cache-file
+The file where the registry will be stored between Gnus sessions. By
+default the file name is @code{.gnus.registry.eieio} in the same
+directory as your @code{.newsrc.eld}.
+@end defvar
+
+@node Registry Article Refer Method
+@subsection Fetching by @code{Message-ID} Using the Registry
+
+The registry knows how to map each @code{Message-ID} to the group it's
+in. This can be leveraged to enhance the ``article refer method'',
+the thing that tells Gnus how to look up an article given its
+Message-ID (@pxref{Finding the Parent}).
+
+@vindex nnregistry
+@vindex gnus-refer-article-method
+
+The @code{nnregistry} refer method does exactly that. It has the
+advantage that an article may be found regardless of the group it's
+in---provided its @code{Message-ID} is known to the registry. It can
+be enabled by augmenting the start-up file with something along these
+lines:
+
+@example
+;; Keep enough entries to have a good hit rate when referring to an
+;; article using the registry. Use long group names so that Gnus
+;; knows where the article is.
+(setq gnus-registry-max-entries 2500)
+
+(gnus-registry-initialize)
+
+(setq gnus-refer-article-method
+ '(current
+ (nnregistry)
+ (nnweb "gmane" (nnweb-type gmane))))
+@end example
+
+The example above instructs Gnus to first look up the article in the
+current group, or, alternatively, using the registry, and finally, if
+all else fails, using Gmane.
+
+@node Fancy splitting to parent
+@subsection Fancy splitting to parent
+
+Simply put, this lets you put followup e-mail where it belongs.
+
+Every message has a Message-ID, which is unique, and the registry
+remembers it. When the message is moved or copied, the registry will
+notice this and offer the new group as a choice to the splitting
+strategy.
+
+When a followup is made, usually it mentions the original message's
+Message-ID in the headers. The registry knows this and uses that
+mention to find the group where the original message lives. You only
+have to put a rule like this:
+
+@lisp
+(setq nnimap-my-split-fancy '(|
+
+ ;; split to parent: you need this
+ (: gnus-registry-split-fancy-with-parent)
+
+ ;; other rules, as an example
+ (: spam-split)
+ ;; default mailbox
+ "mail")
+@end lisp
+
+in your fancy split setup. In addition, you may want to customize the
+following variables.
+
+@defvar gnus-registry-track-extra
+This is a list of symbols, so it's best to change it from the
+Customize interface. By default it's @code{(subject sender recipient)},
+which may work for you. It can be annoying if your mail flow is large
+and people don't stick to the same groups.
+
+When you decide to stop tracking any of those extra data, you can use
+the command @code{gnus-registry-remove-extra-data} to purge it from
+the existing registry entries.
+@end defvar
+
+@defvar gnus-registry-split-strategy
+This is a symbol, so it's best to change it from the Customize
+interface. By default it's @code{nil}, but you may want to set it to
+@code{majority} or @code{first} to split by sender or subject based on
+the majority of matches or on the first found. I find @code{majority}
+works best.
+@end defvar
+
+@node Store custom flags and keywords
+@subsection Store custom flags and keywords
+
+The registry lets you set custom flags and keywords per message. You
+can use the Gnus->Registry Marks menu or the @kbd{M M x} keyboard
+shortcuts, where @code{x} is the first letter of the mark's name.
+
+@defvar gnus-registry-marks
+The custom marks that the registry can use. You can modify the
+default list, if you like. If you do, you'll have to exit Emacs
+before they take effect (you can also unload the registry and reload
+it or evaluate the specific macros you'll need, but you probably don't
+want to bother). Use the Customize interface to modify the list.
+
+By default this list has the @code{Important}, @code{Work},
+@code{Personal}, @code{To-Do}, and @code{Later} marks. They all have
+keyboard shortcuts like @kbd{M M i} for Important, using the first
+letter.
+@end defvar
+
+@defun gnus-registry-mark-article
+Call this function to mark an article with a custom registry mark. It
+will offer the available marks for completion.
+@end defun
+
+You can use @code{defalias} to install a summary line formatting
+function that will show the registry marks. There are two flavors of
+this function, either showing the marks as single characters, using
+their @code{:char} property, or showing the marks as full strings.
+
+@lisp
+;; show the marks as single characters (see the :char property in
+;; 'gnus-registry-marks'):
+;; (defalias 'gnus-user-format-function-M 'gnus-registry-article-marks-to-chars)
+
+;; show the marks by name (see 'gnus-registry-marks'):
+;; (defalias 'gnus-user-format-function-M 'gnus-registry-article-marks-to-names)
+@end lisp
+
+
+@node Store arbitrary data
+@subsection Store arbitrary data
+
+The registry has a simple API that uses a Message-ID as the key to
+store arbitrary data (as long as it can be converted to a list for
+storage).
+
+@defun gnus-registry-set-id-key (id key value)
+Store @code{value} under @code{key} for message @code{id}.
+@end defun
+
+@defun gnus-registry-get-id-key (id key)
+Get the data under @code{key} for message @code{id}.
+@end defun
+
+@defvar gnus-registry-extra-entries-precious
+If any extra entries are precious, their presence will make the
+registry keep the whole entry forever, even if there are no groups for
+the Message-ID and if the size limit of the registry is reached. By
+default this is just @code{(marks)} so the custom registry marks are
+precious.
+@end defvar
+
+@node Other modes
+@section Interaction with other modes
+
+@subsection Dired
+@cindex dired
+
+@code{gnus-dired-minor-mode} provides some useful functions for dired
+buffers. It is enabled with
+@lisp
+(add-hook 'dired-mode-hook 'turn-on-gnus-dired-mode)
+@end lisp
+
+@table @kbd
+@item C-c C-m C-a
+@findex gnus-dired-attach
+@cindex attachments, selection via dired
+Send dired's marked files as an attachment (@code{gnus-dired-attach}).
+You will be prompted for a message buffer.
+
+@item C-c C-m C-l
+@findex gnus-dired-find-file-mailcap
+Visit a file according to the appropriate mailcap entry
+(@code{gnus-dired-find-file-mailcap}). With prefix, open file in a new
+buffer.
+
+@item C-c C-m C-p
+@findex gnus-dired-print
+Print file according to the mailcap entry (@code{gnus-dired-print}). If
+there is no print command, print in a PostScript image.
+@end table
+
+@node Various Various
+@section Various Various
+@cindex mode lines
+@cindex highlights
+
+@table @code
+
+@item gnus-home-directory
+@vindex gnus-home-directory
+All Gnus file and directory variables will be initialized from this
+variable, which defaults to @file{~/}.
+
+@item gnus-directory
+@vindex gnus-directory
+Most Gnus storage file and directory variables will be initialized from
+this variable, which defaults to the @env{SAVEDIR} environment
+variable, or @file{~/News/} if that variable isn't set.
+
+Note that Gnus is mostly loaded when the @file{~/.gnus.el} file is read.
+This means that other directory variables that are initialized from this
+variable won't be set properly if you set this variable in
+@file{~/.gnus.el}. Set this variable in @file{.emacs} instead.
+
+@item gnus-default-directory
+@vindex gnus-default-directory
+Not related to the above variable at all---this variable says what the
+default directory of all Gnus buffers should be. If you issue commands
+like @kbd{C-x C-f}, the prompt you'll get starts in the current buffer's
+default directory. If this variable is @code{nil} (which is the
+default), the default directory will be the default directory of the
+buffer you were in when you started Gnus.
+
+@item gnus-verbose
+@vindex gnus-verbose
+This variable is an integer between zero and ten. The higher the value,
+the more messages will be displayed. If this variable is zero, Gnus
+will never flash any messages, if it is seven (which is the default),
+most important messages will be shown, and if it is ten, Gnus won't ever
+shut up, but will flash so many messages it will make your head swim.
+
+@item gnus-verbose-backends
+@vindex gnus-verbose-backends
+This variable works the same way as @code{gnus-verbose}, but it applies
+to the Gnus back ends instead of Gnus proper.
+
+@item gnus-add-timestamp-to-message
+@vindex gnus-add-timestamp-to-message
+This variable controls whether to add timestamps to messages that are
+controlled by @code{gnus-verbose} and @code{gnus-verbose-backends} and
+are issued. The default value is @code{nil} which means never to add
+timestamp. If it is @code{log}, add timestamps to only the messages
+that go into the @file{*Messages*} buffer (in XEmacs, it is the
+@w{@file{ *Message-Log*}} buffer). If it is neither @code{nil} nor
+@code{log}, add timestamps not only to log messages but also to the ones
+displayed in the echo area.
+
+@item nnheader-max-head-length
+@vindex nnheader-max-head-length
+When the back ends read straight heads of articles, they all try to read
+as little as possible. This variable (default 8192) specifies
+the absolute max length the back ends will try to read before giving up
+on finding a separator line between the head and the body. If this
+variable is @code{nil}, there is no upper read bound. If it is
+@code{t}, the back ends won't try to read the articles piece by piece,
+but read the entire articles. This makes sense with some versions of
+@code{ange-ftp} or @code{efs}.
+
+@item nnheader-head-chop-length
+@vindex nnheader-head-chop-length
+This variable (default 2048) says how big a piece of each article to
+read when doing the operation described above.
+
+@item nnheader-file-name-translation-alist
+@vindex nnheader-file-name-translation-alist
+@cindex file names
+@cindex invalid characters in file names
+@cindex characters in file names
+This is an alist that says how to translate characters in file names.
+For instance, if @samp{:} is invalid as a file character in file names
+on your system (you OS/2 user you), you could say something like:
+
+@lisp
+@group
+(setq nnheader-file-name-translation-alist
+ '((?: . ?_)))
+@end group
+@end lisp
+
+In fact, this is the default value for this variable on OS/2 and MS
+Windows (phooey) systems.
+
+@item gnus-hidden-properties
+@vindex gnus-hidden-properties
+This is a list of properties to use to hide ``invisible'' text. It is
+@code{(invisible t intangible t)} by default on most systems, which
+makes invisible text invisible and intangible.
+
+@item gnus-parse-headers-hook
+@vindex gnus-parse-headers-hook
+A hook called before parsing headers. It can be used, for instance, to
+gather statistics on the headers fetched, or perhaps you'd like to prune
+some headers. I don't see why you'd want that, though.
+
+@item gnus-shell-command-separator
+@vindex gnus-shell-command-separator
+String used to separate two shell commands. The default is @samp{;}.
+
+@item gnus-invalid-group-regexp
+@vindex gnus-invalid-group-regexp
+
+Regexp to match ``invalid'' group names when querying user for a group
+name. The default value catches some @strong{really} invalid group
+names who could possibly mess up Gnus internally (like allowing
+@samp{:} in a group name, which is normally used to delimit method and
+group).
+
+@acronym{IMAP} users might want to allow @samp{/} in group names though.
+
+@item gnus-safe-html-newsgroups
+@vindex gnus-safe-html-newsgroups
+Groups in which links in html articles are considered all safe. The
+value may be a regexp matching those groups, a list of group names, or
+@code{nil}. This overrides @code{mm-w3m-safe-url-regexp}. The default
+value is @code{"\\`nnrss[+:]"}. This is effective only when emacs-w3m
+renders html articles, i.e., in the case @code{mm-text-html-renderer} is
+set to @code{w3m}. @xref{Display Customization, ,Display Customization,
+emacs-mime, The Emacs MIME Manual}.
+
+@end table
+
+@node The End
+@chapter The End
+
+Well, that's the manual---you can get on with your life now. Keep in
+touch. Say hello to your cats from me.
+
+My @strong{ghod}---I just can't stand goodbyes. Sniffle.
+
+Ol' Charles Reznikoff said it pretty well, so I leave the floor to him:
+
+@quotation
+@strong{Te Deum}
+
+@sp 1
+Not because of victories @*
+I sing,@*
+having none,@*
+but for the common sunshine,@*
+the breeze,@*
+the largess of the spring.
+
+@sp 1
+Not for victory@*
+but for the day's work done@*
+as well as I was able;@*
+not for a seat upon the dais@*
+but at the common table.@*
+@end quotation
+
+
+@node Appendices
+@chapter Appendices
+
+@menu
+* XEmacs:: Requirements for installing under XEmacs.
+* History:: How Gnus got where it is today.
+* On Writing Manuals:: Why this is not a beginner's guide.
+* Terminology:: We use really difficult, like, words here.
+* Customization:: Tailoring Gnus to your needs.
+* Troubleshooting:: What you might try if things do not work.
+* Gnus Reference Guide:: Rilly, rilly technical stuff.
+* Emacs for Heathens:: A short introduction to Emacsian terms.
+* Frequently Asked Questions:: The Gnus FAQ
+@end menu
+
+
+@node XEmacs
+@section XEmacs
+@cindex XEmacs
+@cindex installing under XEmacs
+
+XEmacs is distributed as a collection of packages. You should install
+whatever packages the Gnus XEmacs package requires. The current
+requirements are @samp{gnus}, @samp{mail-lib}, @samp{xemacs-base},
+@samp{eterm}, @samp{sh-script}, @samp{net-utils}, @samp{os-utils},
+@samp{dired}, @samp{mh-e}, @samp{sieve}, @samp{ps-print},
+@samp{pgg}, @samp{mailcrypt}, @samp{ecrypto}, and @samp{sasl}.
+
+
+@node History
+@section History
+
+@cindex history
+@sc{gnus} was written by Masanobu @sc{Umeda}. When autumn crept up in
+'94, Lars Magne Ingebrigtsen grew bored and decided to rewrite Gnus.
+
+If you want to investigate the person responsible for this outrage,
+you can point your (feh!) web browser to
+@uref{http://quimby.gnus.org/}. This is also the primary
+distribution point for the new and spiffy versions of Gnus, and is
+known as The Site That Destroys Newsrcs And Drives People Mad.
+
+During the first extended alpha period of development, the new Gnus was
+called ``(ding) Gnus''. @dfn{(ding)} is, of course, short for
+@dfn{ding is not Gnus}, which is a total and utter lie, but who cares?
+(Besides, the ``Gnus'' in this abbreviation should probably be
+pronounced ``news'' as @sc{Umeda} intended, which makes it a more
+appropriate name, don't you think?)
+
+In any case, after spending all that energy on coming up with a new and
+spunky name, we decided that the name was @emph{too} spunky, so we
+renamed it back again to ``Gnus''. But in mixed case. ``Gnus'' vs.
+``@sc{gnus}''. New vs. old.
+
+@menu
+* Gnus Versions:: What Gnus versions have been released.
+* Why?:: What's the point of Gnus?
+* Compatibility:: Just how compatible is Gnus with @sc{gnus}?
+* Conformity:: Gnus tries to conform to all standards.
+* Emacsen:: Gnus can be run on a few modern Emacsen.
+* Gnus Development:: How Gnus is developed.
+* Contributors:: Oodles of people.
+* New Features:: Pointers to some of the new stuff in Gnus.
+@end menu
+
+
+@node Gnus Versions
+@subsection Gnus Versions
+@cindex ding Gnus
+@cindex September Gnus
+@cindex Red Gnus
+@cindex Quassia Gnus
+@cindex Pterodactyl Gnus
+@cindex Oort Gnus
+@cindex No Gnus
+@cindex Ma Gnus
+@cindex Gnus versions
+
+The first ``proper'' release of Gnus 5 was done in November 1995 when it
+was included in the Emacs 19.30 distribution (132 (ding) Gnus releases
+plus 15 Gnus 5.0 releases).
+
+In May 1996 the next Gnus generation (aka. ``September Gnus'' (after 99
+releases)) was released under the name ``Gnus 5.2'' (40 releases).
+
+On July 28th 1996 work on Red Gnus was begun, and it was released on
+January 25th 1997 (after 84 releases) as ``Gnus 5.4'' (67 releases).
+
+On September 13th 1997, Quassia Gnus was started and lasted 37 releases.
+It was released as ``Gnus 5.6'' on March 8th 1998 (46 releases).
+
+Gnus 5.6 begat Pterodactyl Gnus on August 29th 1998 and was released as
+``Gnus 5.8'' (after 99 releases and a CVS repository) on December 3rd
+1999.
+
+On the 26th of October 2000, Oort Gnus was begun and was released as
+Gnus 5.10 on May 1st 2003 (24 releases).
+
+On the January 4th 2004, No Gnus was begun.
+
+On April 19, 2010 Gnus development was moved to Git. See
+http://git.gnus.org for details (http://www.gnus.org will be updated
+with the information when possible).
+
+On the January 31th 2012, Ma Gnus was begun.
+
+If you happen upon a version of Gnus that has a prefixed name---``(ding)
+Gnus'', ``September Gnus'', ``Red Gnus'', ``Quassia Gnus'',
+``Pterodactyl Gnus'', ``Oort Gnus'', ``No Gnus'', ``Ma Gnus''---don't
+panic. Don't let it know that you're frightened. Back away. Slowly.
+Whatever you do, don't run. Walk away, calmly, until you're out of
+its reach. Find a proper released version of Gnus and snuggle up to
+that instead.
+
+
+@node Why?
+@subsection Why?
+
+What's the point of Gnus?
+
+I want to provide a ``rad'', ``happening'', ``way cool'' and ``hep''
+newsreader, that lets you do anything you can think of. That was my
+original motivation, but while working on Gnus, it has become clear to
+me that this generation of newsreaders really belong in the stone age.
+Newsreaders haven't developed much since the infancy of the net. If the
+volume continues to rise with the current rate of increase, all current
+newsreaders will be pretty much useless. How do you deal with
+newsgroups that have thousands of new articles each day? How do you
+keep track of millions of people who post?
+
+Gnus offers no real solutions to these questions, but I would very much
+like to see Gnus being used as a testing ground for new methods of
+reading and fetching news. Expanding on @sc{Umeda}-san's wise decision
+to separate the newsreader from the back ends, Gnus now offers a simple
+interface for anybody who wants to write new back ends for fetching mail
+and news from different sources. I have added hooks for customizations
+everywhere I could imagine it being useful. By doing so, I'm inviting
+every one of you to explore and invent.
+
+May Gnus never be complete. @kbd{C-u 100 M-x all-hail-emacs} and
+@kbd{C-u 100 M-x all-hail-xemacs}.
+
+
+@node Compatibility
+@subsection Compatibility
+
+@cindex compatibility
+Gnus was designed to be fully compatible with @sc{gnus}. Almost all key
+bindings have been kept. More key bindings have been added, of course,
+but only in one or two obscure cases have old bindings been changed.
+
+Our motto is:
+@quotation
+@cartouche
+@center In a cloud bones of steel.
+@end cartouche
+@end quotation
+
+All commands have kept their names. Some internal functions have changed
+their names.
+
+The @code{gnus-uu} package has changed drastically. @xref{Decoding
+Articles}.
+
+One major compatibility question is the presence of several summary
+buffers. All variables relevant while reading a group are
+buffer-local to the summary buffer they belong in. Although many
+important variables have their values copied into their global
+counterparts whenever a command is executed in the summary buffer, this
+change might lead to incorrect values being used unless you are careful.
+
+All code that relies on knowledge of @sc{gnus} internals will probably
+fail. To take two examples: Sorting @code{gnus-newsrc-alist} (or
+changing it in any way, as a matter of fact) is strictly verboten. Gnus
+maintains a hash table that points to the entries in this alist (which
+speeds up many functions), and changing the alist directly will lead to
+peculiar results.
+
+@cindex hilit19
+@cindex highlighting
+Old hilit19 code does not work at all. In fact, you should probably
+remove all hilit code from all Gnus hooks
+(@code{gnus-group-prepare-hook} and @code{gnus-summary-prepare-hook}).
+Gnus provides various integrated functions for highlighting. These are
+faster and more accurate. To make life easier for everybody, Gnus will
+by default remove all hilit calls from all hilit hooks. Uncleanliness!
+Away!
+
+Packages like @code{expire-kill} will no longer work. As a matter of
+fact, you should probably remove all old @sc{gnus} packages (and other
+code) when you start using Gnus. More likely than not, Gnus already
+does what you have written code to make @sc{gnus} do. (Snicker.)
+
+Even though old methods of doing things are still supported, only the
+new methods are documented in this manual. If you detect a new method of
+doing something while reading this manual, that does not mean you have
+to stop doing it the old way.
+
+Gnus understands all @sc{gnus} startup files.
+
+@kindex M-x gnus-bug
+@findex gnus-bug
+@cindex reporting bugs
+@cindex bugs
+Overall, a casual user who hasn't written much code that depends on
+@sc{gnus} internals should suffer no problems. If problems occur,
+please let me know by issuing that magic command @kbd{M-x gnus-bug}.
+
+@vindex gnus-bug-create-help-buffer
+If you are in the habit of sending bug reports @emph{very} often, you
+may find the helpful help buffer annoying after a while. If so, set
+@code{gnus-bug-create-help-buffer} to @code{nil} to avoid having it pop
+up at you.
+
+
+@node Conformity
+@subsection Conformity
+
+No rebels without a clue here, ma'am. We conform to all standards known
+to (wo)man. Except for those standards and/or conventions we disagree
+with, of course.
+
+@table @strong
+
+@item RFC (2)822
+@cindex RFC 822
+@cindex RFC 2822
+There are no known breaches of this standard.
+
+@item RFC 1036
+@cindex RFC 1036
+There are no known breaches of this standard, either.
+
+@item Son-of-RFC 1036
+@cindex Son-of-RFC 1036
+We do have some breaches to this one.
+
+@table @emph
+
+@item X-Newsreader
+@itemx User-Agent
+These are considered to be ``vanity headers'', while I consider them
+to be consumer information. After seeing so many badly formatted
+articles coming from @code{tin} and @code{Netscape} I know not to use
+either of those for posting articles. I would not have known that if
+it wasn't for the @code{X-Newsreader} header.
+@end table
+
+@item USEFOR
+@cindex USEFOR
+USEFOR is an IETF working group writing a successor to RFC 1036, based
+on Son-of-RFC 1036. They have produced a number of drafts proposing
+various changes to the format of news articles. The Gnus towers will
+look into implementing the changes when the draft is accepted as an RFC.
+
+@item MIME---RFC 2045--2049 etc
+@cindex @acronym{MIME}
+All the various @acronym{MIME} RFCs are supported.
+
+@item Disposition Notifications---RFC 2298
+Message Mode is able to request notifications from the receiver.
+
+@item PGP---RFC 1991 and RFC 2440
+@cindex RFC 1991
+@cindex RFC 2440
+RFC 1991 is the original @acronym{PGP} message specification,
+published as an informational RFC@. RFC 2440 was the follow-up, now
+called Open PGP, and put on the Standards Track. Both document a
+non-@acronym{MIME} aware @acronym{PGP} format. Gnus supports both
+encoding (signing and encryption) and decoding (verification and
+decryption).
+
+@item PGP/MIME---RFC 2015/3156
+RFC 2015 (superseded by 3156 which references RFC 2440 instead of RFC
+1991) describes the @acronym{MIME}-wrapping around the RFC 1991/2440 format.
+Gnus supports both encoding and decoding.
+
+@item S/MIME---RFC 2633
+RFC 2633 describes the @acronym{S/MIME} format.
+
+@item IMAP---RFC 1730/2060, RFC 2195, RFC 2086, RFC 2359, RFC 2595, RFC 1731
+RFC 1730 is @acronym{IMAP} version 4, updated somewhat by RFC 2060
+(@acronym{IMAP} 4 revision 1). RFC 2195 describes CRAM-MD5
+authentication for @acronym{IMAP}. RFC 2086 describes access control
+lists (ACLs) for @acronym{IMAP}. RFC 2359 describes a @acronym{IMAP}
+protocol enhancement. RFC 2595 describes the proper @acronym{TLS}
+integration (STARTTLS) with @acronym{IMAP}. RFC 1731 describes the
+GSSAPI/Kerberos4 mechanisms for @acronym{IMAP}.
+
+@end table
+
+If you ever notice Gnus acting non-compliant with regards to the texts
+mentioned above, don't hesitate to drop a note to Gnus Towers and let us
+know.
+
+
+@node Emacsen
+@subsection Emacsen
+@cindex Emacsen
+@cindex XEmacs
+@cindex Mule
+@cindex Emacs
+
+This version of Gnus should work on:
+
+@itemize @bullet
+
+@item
+Emacs 23.1 and up.
+
+@item
+XEmacs 21.4 and up.
+
+@end itemize
+
+This Gnus version will absolutely not work on any Emacsen older than
+that. Not reliably, at least. Older versions of Gnus may work on older
+Emacs versions. Particularly, Gnus 5.10.8 should also work on Emacs
+20.7 and XEmacs 21.1.
+
+@c No-merge comment: The paragraph added in v5-10 here must not be
+@c synced here!
+
+@node Gnus Development
+@subsection Gnus Development
+
+Gnus is developed in a two-phased cycle. The first phase involves much
+discussion on the development mailing list @samp{ding@@gnus.org}, where people
+propose changes and new features, post patches and new back ends. This
+phase is called the @dfn{alpha} phase, since the Gnusae released in this
+phase are @dfn{alpha releases}, or (perhaps more commonly in other
+circles) @dfn{snapshots}. During this phase, Gnus is assumed to be
+unstable and should not be used by casual users. Gnus alpha releases
+have names like ``Oort Gnus'' and ``No Gnus''. @xref{Gnus Versions}.
+
+After futzing around for 10--100 alpha releases, Gnus is declared
+@dfn{frozen}, and only bug fixes are applied. Gnus loses the prefix,
+and is called things like ``Gnus 5.10.1'' instead. Normal people are
+supposed to be able to use these, and these are mostly discussed on the
+@samp{gnu.emacs.gnus} newsgroup. This newgroup is mirrored to the
+mailing list @samp{info-gnus-english@@gnu.org} which is carried on Gmane
+as @samp{gmane.emacs.gnus.user}. These releases are finally integrated
+in Emacs.
+
+@cindex Incoming*
+@vindex mail-source-delete-incoming
+Some variable defaults differ between alpha Gnusae and released Gnusae,
+in particular, @code{mail-source-delete-incoming}. This is to prevent
+lossage of mail if an alpha release hiccups while handling the mail.
+@xref{Mail Source Customization}.
+
+The division of discussion between the ding mailing list and the Gnus
+newsgroup is not purely based on publicity concerns. It's true that
+having people write about the horrible things that an alpha Gnus release
+can do (sometimes) in a public forum may scare people off, but more
+importantly, talking about new experimental features that have been
+introduced may confuse casual users. New features are frequently
+introduced, fiddled with, and judged to be found wanting, and then
+either discarded or totally rewritten. People reading the mailing list
+usually keep up with these rapid changes, while people on the newsgroup
+can't be assumed to do so.
+
+So if you have problems with or questions about the alpha versions,
+direct those to the ding mailing list @samp{ding@@gnus.org}. This list
+is also available on Gmane as @samp{gmane.emacs.gnus.general}.
+
+@cindex Incoming*
+@vindex mail-source-delete-incoming
+Some variable defaults differ between alpha Gnusae and released Gnusae,
+in particular, @code{mail-source-delete-incoming}. This is to prevent
+lossage of mail if an alpha release hiccups while handling the mail.
+@xref{Mail Source Customization}.
+
+@node Contributors
+@subsection Contributors
+@cindex contributors
+
+The new Gnus version couldn't have been done without the help of all the
+people on the (ding) mailing list. Every day for over a year I have
+gotten billions of nice bug reports from them, filling me with joy,
+every single one of them. Smooches. The people on the list have been
+tried beyond endurance, what with my ``oh, that's a neat idea <type
+type>, yup, I'll release it right away <ship off> no wait, that doesn't
+work at all <type type>, yup, I'll ship that one off right away <ship
+off> no, wait, that absolutely does not work'' policy for releases.
+Micro$oft---bah. Amateurs. I'm @emph{much} worse. (Or is that
+``worser''? ``much worser''? ``worsest''?)
+
+I would like to take this opportunity to thank the Academy for@dots{} oops,
+wrong show.
+
+@itemize @bullet
+
+@item
+Masanobu @sc{Umeda}---the writer of the original @sc{gnus}.
+
+@item
+Shenghuo Zhu---uudecode.el, mm-uu.el, rfc1843.el,
+nnwarchive and many, many other things connected with @acronym{MIME} and
+other types of en/decoding, as well as general bug fixing, new
+functionality and stuff.
+
+@item
+Per Abrahamsen---custom, scoring, highlighting and @sc{soup} code (as
+well as numerous other things).
+
+@item
+Luis Fernandes---design and graphics.
+
+@item
+Joe Reiss---creator of the smiley faces.
+
+@item
+Justin Sheehy---the @acronym{FAQ} maintainer.
+
+@item
+Erik Naggum---help, ideas, support, code and stuff.
+
+@item
+Wes Hardaker---@file{gnus-picon.el} and the manual section on
+@dfn{picons} (@pxref{Picons}).
+
+@item
+Kim-Minh Kaplan---further work on the picon code.
+
+@item
+Brad Miller---@file{gnus-gl.el} and the GroupLens manual section.
+
+@item
+Sudish Joseph---innumerable bug fixes.
+
+@item
+Ilja Weis---@file{gnus-topic.el}.
+
+@item
+Steven L. Baur---lots and lots and lots of bug detection and fixes.
+
+@item
+Vladimir Alexiev---the refcard and reference booklets.
+
+@item
+Felix Lee & Jamie Zawinski---I stole some pieces from the XGnus
+distribution by Felix Lee and JWZ.
+
+@item
+Scott Byer---@file{nnfolder.el} enhancements & rewrite.
+
+@item
+Peter Mutsaers---orphan article scoring code.
+
+@item
+Ken Raeburn---POP mail support.
+
+@item
+Hallvard B Furuseth---various bits and pieces, especially dealing with
+.newsrc files.
+
+@item
+Brian Edmonds---@file{gnus-bbdb.el}.
+
+@item
+David Moore---rewrite of @file{nnvirtual.el} and many other things.
+
+@item
+Kevin Davidson---came up with the name @dfn{ding}, so blame him.
+
+@item
+François Pinard---many, many interesting and thorough bug reports, as
+well as autoconf support.
+
+@end itemize
+
+This manual was proof-read by Adrian Aichner, with Ricardo Nassif, Mark
+Borges, and Jost Krieger proof-reading parts of the manual.
+
+The following people have contributed many patches and suggestions:
+
+Christopher Davis,
+Andrew Eskilsson,
+Kai Grossjohann,
+Kevin Greiner,
+Jesper Harder,
+Paul Jarc,
+Simon Josefsson,
+David K@aa{}gedal,
+Richard Pieri,
+Fabrice Popineau,
+Daniel Quinlan,
+Michael Shields,
+Reiner Steib,
+Jason L. Tibbitts, III,
+Jack Vinson,
+Katsumi Yamaoka, @c Yamaoka
+and
+Teodor Zlatanov.
+
+Also thanks to the following for patches and stuff:
+
+Jari Aalto,
+Adrian Aichner,
+Vladimir Alexiev,
+Russ Allbery,
+Peter Arius,
+Matt Armstrong,
+Marc Auslander,
+Miles Bader,
+Alexei V. Barantsev,
+Frank Bennett,
+Robert Bihlmeyer,
+Chris Bone,
+Mark Borges,
+Mark Boyns,
+Lance A. Brown,
+Rob Browning,
+Kees de Bruin,
+Martin Buchholz,
+Joe Buehler,
+Kevin Buhr,
+Alastair Burt,
+Joao Cachopo,
+Zlatko Calusic,
+Massimo Campostrini,
+Castor,
+David Charlap,
+Dan Christensen,
+Kevin Christian,
+Jae-you Chung, @c ?
+James H. Cloos, Jr.,
+Laura Conrad,
+Michael R. Cook,
+Glenn Coombs,
+Andrew J. Cosgriff,
+Neil Crellin,
+Frank D. Cringle,
+Geoffrey T. Dairiki,
+Andre Deparade,
+Ulrik Dickow,
+Dave Disser,
+Rui-Tao Dong, @c ?
+Joev Dubach,
+Michael Welsh Duggan,
+Dave Edmondson,
+Paul Eggert,
+Mark W. Eichin,
+Karl Eichwalder,
+Enami Tsugutomo, @c Enami
+Michael Ernst,
+Luc Van Eycken,
+Sam Falkner,
+Nelson Jose dos Santos Ferreira,
+Sigbjorn Finne,
+Sven Fischer,
+Paul Fisher,
+Decklin Foster,
+Gary D. Foster,
+Paul Franklin,
+Guy Geens,
+Arne Georg Gleditsch,
+David S. Goldberg,
+Michelangelo Grigni,
+Dale Hagglund,
+D. Hall,
+Magnus Hammerin,
+Kenichi Handa, @c Handa
+Raja R. Harinath,
+Yoshiki Hayashi, @c Hayashi
+P. E. Jareth Hein,
+Hisashige Kenji, @c Hisashige
+Scott Hofmann,
+Tassilo Horn,
+Marc Horowitz,
+Gunnar Horrigmo,
+Richard Hoskins,
+Brad Howes,
+Miguel de Icaza,
+François Felix Ingrand,
+Tatsuya Ichikawa, @c Ichikawa
+Ishikawa Ichiro, @c Ishikawa
+Lee Iverson,
+Iwamuro Motonori, @c Iwamuro
+Rajappa Iyer,
+Andreas Jaeger,
+Adam P. Jenkins,
+Randell Jesup,
+Fred Johansen,
+Gareth Jones,
+Greg Klanderman,
+Karl Kleinpaste,
+Michael Klingbeil,
+Peter Skov Knudsen,
+Shuhei Kobayashi, @c Kobayashi
+Petr Konecny,
+Koseki Yoshinori, @c Koseki
+Thor Kristoffersen,
+Jens Lautenbacher,
+Martin Larose,
+Seokchan Lee, @c Lee
+Joerg Lenneis,
+Carsten Leonhardt,
+James LewisMoss,
+Christian Limpach,
+Markus Linnala,
+Dave Love,
+Mike McEwan,
+Tonny Madsen,
+Shlomo Mahlab,
+Nat Makarevitch,
+Istvan Marko,
+David Martin,
+Jason R. Mastaler,
+Gordon Matzigkeit,
+Timo Metzemakers,
+Richard Mlynarik,
+Lantz Moore,
+Morioka Tomohiko, @c Morioka
+Erik Toubro Nielsen,
+Hrvoje Niksic,
+Andy Norman,
+Fred Oberhauser,
+C. R. Oldham,
+Alexandre Oliva,
+Ken Olstad,
+Masaharu Onishi, @c Onishi
+Hideki Ono, @c Ono
+Ettore Perazzoli,
+William Perry,
+Stephen Peters,
+Jens-Ulrik Holger Petersen,
+Ulrich Pfeifer,
+Matt Pharr,
+Andy Piper,
+John McClary Prevost,
+Bill Pringlemeir,
+Mike Pullen,
+Jim Radford,
+Colin Rafferty,
+Lasse Rasinen,
+Lars Balker Rasmussen,
+Joe Reiss,
+Renaud Rioboo,
+Roland B. Roberts,
+Bart Robinson,
+Christian von Roques,
+Markus Rost,
+Jason Rumney,
+Wolfgang Rupprecht,
+Jay Sachs,
+Dewey M. Sasser,
+Conrad Sauerwald,
+Loren Schall,
+Dan Schmidt,
+Ralph Schleicher,
+Philippe Schnoebelen,
+Andreas Schwab,
+Randal L. Schwartz,
+Danny Siu,
+Matt Simmons,
+Paul D. Smith,
+Jeff Sparkes,
+Toby Speight,
+Michael Sperber,
+Darren Stalder,
+Richard Stallman,
+Greg Stark,
+Sam Steingold,
+Paul Stevenson,
+Jonas Steverud,
+Paul Stodghill,
+Kiyokazu Suto, @c Suto
+Kurt Swanson,
+Samuel Tardieu,
+Teddy,
+Chuck Thompson,
+Tozawa Akihiko, @c Tozawa
+Philippe Troin,
+James Troup,
+Trung Tran-Duc,
+Jack Twilley,
+Aaron M. Ucko,
+Aki Vehtari,
+Didier Verna,
+Vladimir Volovich,
+Jan Vroonhof,
+Stefan Waldherr,
+Pete Ware,
+Barry A. Warsaw,
+Christoph Wedler,
+Joe Wells,
+Lee Willis,
+and
+Lloyd Zusman.
+
+
+For a full overview of what each person has done, the ChangeLogs
+included in the Gnus alpha distributions should give ample reading
+(550kB and counting).
+
+Apologies to everybody that I've forgotten, of which there are many, I'm
+sure.
+
+Gee, that's quite a list of people. I guess that must mean that there
+actually are people who are using Gnus. Who'd'a thunk it!
+
+
+@node New Features
+@subsection New Features
+@cindex new features
+
+@menu
+* ding Gnus:: New things in Gnus 5.0/5.1, the first new Gnus.
+* September Gnus:: The Thing Formally Known As Gnus 5.2/5.3.
+* Red Gnus:: Third time best---Gnus 5.4/5.5.
+* Quassia Gnus:: Two times two is four, or Gnus 5.6/5.7.
+* Pterodactyl Gnus:: Pentad also starts with P, AKA Gnus 5.8/5.9.
+* Oort Gnus:: It's big. It's far out. Gnus 5.10/5.11.
+* No Gnus:: Very punny. Gnus 5.12/5.13.
+* Ma Gnus:: Celebrating 25 years of Gnus.
+@end menu
+
+These lists are, of course, just @emph{short} overviews of the
+@emph{most} important new features. No, really. There are tons more.
+Yes, we have feeping creaturism in full effect.
+
+@node ding Gnus
+@subsubsection (ding) Gnus
+
+New features in Gnus 5.0/5.1:
+
+@itemize @bullet
+
+@item
+The look of all buffers can be changed by setting format-like variables
+(@pxref{Group Buffer Format} and @pxref{Summary Buffer Format}).
+
+@item
+Local spool and several @acronym{NNTP} servers can be used at once
+(@pxref{Select Methods}).
+
+@item
+You can combine groups into virtual groups (@pxref{Virtual Groups}).
+
+@item
+You can read a number of different mail formats (@pxref{Getting Mail}).
+All the mail back ends implement a convenient mail expiry scheme
+(@pxref{Expiring Mail}).
+
+@item
+Gnus can use various strategies for gathering threads that have lost
+their roots (thereby gathering loose sub-threads into one thread) or it
+can go back and retrieve enough headers to build a complete thread
+(@pxref{Customizing Threading}).
+
+@item
+Killed groups can be displayed in the group buffer, and you can read
+them as well (@pxref{Listing Groups}).
+
+@item
+Gnus can do partial group updates---you do not have to retrieve the
+entire active file just to check for new articles in a few groups
+(@pxref{The Active File}).
+
+@item
+Gnus implements a sliding scale of subscribedness to groups
+(@pxref{Group Levels}).
+
+@item
+You can score articles according to any number of criteria
+(@pxref{Scoring}). You can even get Gnus to find out how to score
+articles for you (@pxref{Adaptive Scoring}).
+
+@item
+Gnus maintains a dribble buffer that is auto-saved the normal Emacs
+manner, so it should be difficult to lose much data on what you have
+read if your machine should go down (@pxref{Auto Save}).
+
+@item
+Gnus now has its own startup file (@file{~/.gnus.el}) to avoid
+cluttering up the @file{.emacs} file.
+
+@item
+You can set the process mark on both groups and articles and perform
+operations on all the marked items (@pxref{Process/Prefix}).
+
+@item
+You can list subsets of groups according to, well, anything
+(@pxref{Listing Groups}).
+
+@item
+You can browse foreign servers and subscribe to groups from those
+servers (@pxref{Browse Foreign Server}).
+
+@item
+Gnus can fetch articles, asynchronously, on a second connection to the
+server (@pxref{Asynchronous Fetching}).
+
+@item
+You can cache articles locally (@pxref{Article Caching}).
+
+@item
+The uudecode functions have been expanded and generalized
+(@pxref{Decoding Articles}).
+
+@item
+You can still post uuencoded articles, which was a little-known feature
+of @sc{gnus}' past (@pxref{Uuencoding and Posting}).
+
+@item
+Fetching parents (and other articles) now actually works without
+glitches (@pxref{Finding the Parent}).
+
+@item
+Gnus can fetch @acronym{FAQ}s and group descriptions (@pxref{Group Information}).
+
+@item
+Digests (and other files) can be used as the basis for groups
+(@pxref{Document Groups}).
+
+@item
+Articles can be highlighted and customized (@pxref{Customizing
+Articles}).
+
+@item
+URLs and other external references can be buttonized (@pxref{Article
+Buttons}).
+
+@item
+You can do lots of strange stuff with the Gnus window & frame
+configuration (@pxref{Window Layout}).
+
+@end itemize
+
+
+@node September Gnus
+@subsubsection September Gnus
+
+@iftex
+@iflatex
+\gnusfig{-28cm}{0cm}{\epsfig{figure=ps/september,height=20cm}}
+@end iflatex
+@end iftex
+
+New features in Gnus 5.2/5.3:
+
+@itemize @bullet
+
+@item
+A new message composition mode is used. All old customization variables
+for @code{mail-mode}, @code{rnews-reply-mode} and @code{gnus-msg} are
+now obsolete.
+
+@item
+Gnus is now able to generate @dfn{sparse} threads---threads where
+missing articles are represented by empty nodes (@pxref{Customizing
+Threading}).
+
+@lisp
+(setq gnus-build-sparse-threads 'some)
+@end lisp
+
+@item
+Outgoing articles are stored on a special archive server
+(@pxref{Archived Messages}).
+
+@item
+Partial thread regeneration now happens when articles are
+referred.
+
+@item
+Gnus can make use of GroupLens predictions.
+
+@item
+Picons (personal icons) can be displayed under XEmacs (@pxref{Picons}).
+
+@item
+A @code{trn}-like tree buffer can be displayed (@pxref{Tree Display}).
+
+@lisp
+(setq gnus-use-trees t)
+@end lisp
+
+@item
+An @code{nn}-like pick-and-read minor mode is available for the summary
+buffers (@pxref{Pick and Read}).
+
+@lisp
+(add-hook 'gnus-summary-mode-hook 'gnus-pick-mode)
+@end lisp
+
+@item
+In binary groups you can use a special binary minor mode (@pxref{Binary
+Groups}).
+
+@item
+Groups can be grouped in a folding topic hierarchy (@pxref{Group
+Topics}).
+
+@lisp
+(add-hook 'gnus-group-mode-hook 'gnus-topic-mode)
+@end lisp
+
+@item
+Gnus can re-send and bounce mail (@pxref{Summary Mail Commands}).
+
+@item
+Groups can now have a score, and bubbling based on entry frequency
+is possible (@pxref{Group Score}).
+
+@lisp
+(add-hook 'gnus-summary-exit-hook 'gnus-summary-bubble-group)
+@end lisp
+
+@item
+Groups can be process-marked, and commands can be performed on
+groups of groups (@pxref{Marking Groups}).
+
+@item
+Caching is possible in virtual groups.
+
+@item
+@code{nndoc} now understands all kinds of digests, mail boxes, rnews
+news batches, ClariNet briefs collections, and just about everything
+else (@pxref{Document Groups}).
+
+@item
+Gnus has a new back end (@code{nnsoup}) to create/read SOUP packets.
+
+@item
+The Gnus cache is much faster.
+
+@item
+Groups can be sorted according to many criteria (@pxref{Sorting
+Groups}).
+
+@item
+New group parameters have been introduced to set list-addresses and
+expiry times (@pxref{Group Parameters}).
+
+@item
+All formatting specs allow specifying faces to be used
+(@pxref{Formatting Fonts}).
+
+@item
+There are several more commands for setting/removing/acting on process
+marked articles on the @kbd{M P} submap (@pxref{Setting Process Marks}).
+
+@item
+The summary buffer can be limited to show parts of the available
+articles based on a wide range of criteria. These commands have been
+bound to keys on the @kbd{/} submap (@pxref{Limiting}).
+
+@item
+Articles can be made persistent with the @kbd{*} command
+(@pxref{Persistent Articles}).
+
+@item
+All functions for hiding article elements are now toggles.
+
+@item
+Article headers can be buttonized (@pxref{Article Washing}).
+
+@item
+All mail back ends support fetching articles by @code{Message-ID}.
+
+@item
+Duplicate mail can now be treated properly (@pxref{Duplicates}).
+
+@item
+All summary mode commands are available directly from the article
+buffer (@pxref{Article Keymap}).
+
+@item
+Frames can be part of @code{gnus-buffer-configuration} (@pxref{Window
+Layout}).
+
+@item
+Mail can be re-scanned by a daemonic process (@pxref{Daemons}).
+@iftex
+@iflatex
+\marginpar[\mbox{}\hfill\epsfig{figure=ps/fseptember,height=5cm}]{\epsfig{figure=ps/fseptember,height=5cm}}
+@end iflatex
+@end iftex
+
+@item
+Groups can be made permanently visible (@pxref{Listing Groups}).
+
+@lisp
+(setq gnus-permanently-visible-groups "^nnml:")
+@end lisp
+
+@item
+Many new hooks have been introduced to make customizing easier.
+
+@item
+Gnus respects the @code{Mail-Copies-To} header.
+
+@item
+Threads can be gathered by looking at the @code{References} header
+(@pxref{Customizing Threading}).
+
+@lisp
+(setq gnus-summary-thread-gathering-function
+ 'gnus-gather-threads-by-references)
+@end lisp
+
+@item
+Read articles can be stored in a special backlog buffer to avoid
+refetching (@pxref{Article Backlog}).
+
+@lisp
+(setq gnus-keep-backlog 50)
+@end lisp
+
+@item
+A clean copy of the current article is always stored in a separate
+buffer to allow easier treatment.
+
+@item
+Gnus can suggest where to save articles (@pxref{Saving Articles}).
+
+@item
+Gnus doesn't have to do as much prompting when saving (@pxref{Saving
+Articles}).
+
+@lisp
+(setq gnus-prompt-before-saving t)
+@end lisp
+
+@item
+@code{gnus-uu} can view decoded files asynchronously while fetching
+articles (@pxref{Other Decode Variables}).
+
+@lisp
+(setq gnus-uu-grabbed-file-functions 'gnus-uu-grab-view)
+@end lisp
+
+@item
+Filling in the article buffer now works properly on cited text
+(@pxref{Article Washing}).
+
+@item
+Hiding cited text adds buttons to toggle hiding, and how much
+cited text to hide is now customizable (@pxref{Article Hiding}).
+
+@lisp
+(setq gnus-cited-lines-visible 2)
+@end lisp
+
+@item
+Boring headers can be hidden (@pxref{Article Hiding}).
+
+@item
+Default scoring values can now be set from the menu bar.
+
+@item
+Further syntax checking of outgoing articles have been added.
+
+@end itemize
+
+
+@node Red Gnus
+@subsubsection Red Gnus
+
+New features in Gnus 5.4/5.5:
+
+@iftex
+@iflatex
+\gnusfig{-5.5cm}{-4cm}{\epsfig{figure=ps/red,height=20cm}}
+@end iflatex
+@end iftex
+
+@itemize @bullet
+
+@item
+@file{nntp.el} has been totally rewritten in an asynchronous fashion.
+
+@item
+Article prefetching functionality has been moved up into
+Gnus (@pxref{Asynchronous Fetching}).
+
+@item
+Scoring can now be performed with logical operators like @code{and},
+@code{or}, @code{not}, and parent redirection (@pxref{Advanced
+Scoring}).
+
+@item
+Article washing status can be displayed in the
+article mode line (@pxref{Misc Article}).
+
+@item
+@file{gnus.el} has been split into many smaller files.
+
+@item
+Suppression of duplicate articles based on Message-ID can be done
+(@pxref{Duplicate Suppression}).
+
+@lisp
+(setq gnus-suppress-duplicates t)
+@end lisp
+
+@item
+New variables for specifying what score and adapt files are to be
+considered home score and adapt files (@pxref{Home Score File}) have
+been added.
+
+@item
+@code{nndoc} was rewritten to be easily extensible (@pxref{Document
+Server Internals}).
+
+@item
+Groups can inherit group parameters from parent topics (@pxref{Topic
+Parameters}).
+
+@item
+Article editing has been revamped and is now actually usable.
+
+@item
+Signatures can be recognized in more intelligent fashions
+(@pxref{Article Signature}).
+
+@item
+Summary pick mode has been made to look more @code{nn}-like. Line
+numbers are displayed and the @kbd{.} command can be used to pick
+articles (@code{Pick and Read}).
+
+@item
+Commands for moving the @file{.newsrc.eld} from one server to
+another have been added (@pxref{Changing Servers}).
+
+@item
+There's a way now to specify that ``uninteresting'' fields be suppressed
+when generating lines in buffers (@pxref{Advanced Formatting}).
+
+@item
+Several commands in the group buffer can be undone with @kbd{C-M-_}
+(@pxref{Undo}).
+
+@item
+Scoring can be done on words using the new score type @code{w}
+(@pxref{Score File Format}).
+
+@item
+Adaptive scoring can be done on a Subject word-by-word basis
+(@pxref{Adaptive Scoring}).
+
+@lisp
+(setq gnus-use-adaptive-scoring '(word))
+@end lisp
+
+@item
+Scores can be decayed (@pxref{Score Decays}).
+
+@lisp
+(setq gnus-decay-scores t)
+@end lisp
+
+@item
+Scoring can be performed using a regexp on the Date header. The Date is
+normalized to compact ISO 8601 format first (@pxref{Score File Format}).
+
+@item
+A new command has been added to remove all data on articles from
+the native server (@pxref{Changing Servers}).
+
+@item
+A new command for reading collections of documents
+(@code{nndoc} with @code{nnvirtual} on top) has been added---@kbd{C-M-d}
+(@pxref{Really Various Summary Commands}).
+
+@item
+Process mark sets can be pushed and popped (@pxref{Setting Process
+Marks}).
+
+@item
+A new mail-to-news back end makes it possible to post even when the @acronym{NNTP}
+server doesn't allow posting (@pxref{Mail-To-News Gateways}).
+
+@item
+A new back end for reading searches from Web search engines
+(@dfn{DejaNews}, @dfn{Alta Vista}, @dfn{InReference}) has been added
+(@pxref{Web Searches}).
+
+@item
+Groups inside topics can now be sorted using the standard sorting
+functions, and each topic can be sorted independently (@pxref{Topic
+Sorting}).
+
+@item
+Subsets of the groups can be sorted independently (@code{Sorting
+Groups}).
+
+@item
+Cached articles can be pulled into the groups (@pxref{Summary Generation
+Commands}).
+@iftex
+@iflatex
+\marginpar[\mbox{}\hfill\epsfig{figure=ps/fred,width=3cm}]{\epsfig{figure=ps/fred,width=3cm}}
+@end iflatex
+@end iftex
+
+@item
+Score files are now applied in a more reliable order (@pxref{Score
+Variables}).
+
+@item
+Reports on where mail messages end up can be generated (@pxref{Splitting
+Mail}).
+
+@item
+More hooks and functions have been added to remove junk from incoming
+mail before saving the mail (@pxref{Washing Mail}).
+
+@item
+Emphasized text can be properly fontisized:
+
+@end itemize
+
+
+@node Quassia Gnus
+@subsubsection Quassia Gnus
+
+New features in Gnus 5.6:
+
+@itemize @bullet
+
+@item
+New functionality for using Gnus as an offline newsreader has been
+added. A plethora of new commands and modes have been added.
+@xref{Gnus Unplugged}, for the full story.
+
+@item
+The @code{nndraft} back end has returned, but works differently than
+before. All Message buffers are now also articles in the @code{nndraft}
+group, which is created automatically.
+
+@item
+@code{gnus-alter-header-function} can now be used to alter header
+values.
+
+@item
+@code{gnus-summary-goto-article} now accept Message-IDs.
+
+@item
+A new Message command for deleting text in the body of a message
+outside the region: @kbd{C-c C-v}.
+
+@item
+You can now post to component group in @code{nnvirtual} groups with
+@kbd{C-u C-c C-c}.
+
+@item
+ @code{nntp-rlogin-program}---new variable to ease customization.
+
+@item
+@code{C-u C-c C-c} in @code{gnus-article-edit-mode} will now inhibit
+re-highlighting of the article buffer.
+
+@item
+New element in @code{gnus-boring-article-headers}---@code{long-to}.
+
+@item
+@kbd{M-i} symbolic prefix command. @xref{Symbolic Prefixes}, for
+details.
+
+@item
+@kbd{L} and @kbd{I} in the summary buffer now take the symbolic prefix
+@kbd{a} to add the score rule to the @file{all.SCORE} file.
+
+@item
+@code{gnus-simplify-subject-functions} variable to allow greater
+control over simplification.
+
+@item
+@kbd{A T}---new command for fetching the current thread.
+
+@item
+@kbd{/ T}---new command for including the current thread in the
+limit.
+
+@item
+@kbd{M-RET} is a new Message command for breaking cited text.
+
+@item
+@samp{\\1}-expressions are now valid in @code{nnmail-split-methods}.
+
+@item
+The @code{custom-face-lookup} function has been removed.
+If you used this function in your initialization files, you must
+rewrite them to use @code{face-spec-set} instead.
+
+@item
+Canceling now uses the current select method. Symbolic prefix
+@kbd{a} forces normal posting method.
+
+@item
+New command to translate M******** sm*rtq**t*s into proper
+text---@kbd{W d}.
+
+@item
+For easier debugging of @code{nntp}, you can set
+@code{nntp-record-commands} to a non-@code{nil} value.
+
+@item
+@code{nntp} now uses @file{~/.authinfo}, a @file{.netrc}-like file, for
+controlling where and how to send @sc{authinfo} to @acronym{NNTP} servers.
+
+@item
+A command for editing group parameters from the summary buffer
+has been added.
+
+@item
+A history of where mails have been split is available.
+
+@item
+A new article date command has been added---@code{article-date-iso8601}.
+
+@item
+Subjects can be simplified when threading by setting
+@code{gnus-score-thread-simplify}.
+
+@item
+A new function for citing in Message has been
+added---@code{message-cite-original-without-signature}.
+
+@item
+@code{article-strip-all-blank-lines}---new article command.
+
+@item
+A new Message command to kill to the end of the article has
+been added.
+
+@item
+A minimum adaptive score can be specified by using the
+@code{gnus-adaptive-word-minimum} variable.
+
+@item
+The ``lapsed date'' article header can be kept continually
+updated by the @code{gnus-start-date-timer} command.
+
+@item
+Web listserv archives can be read with the @code{nnlistserv} back end.
+
+@item
+Old dejanews archives can now be read by @code{nnweb}.
+
+@end itemize
+
+@node Pterodactyl Gnus
+@subsubsection Pterodactyl Gnus
+
+New features in Gnus 5.8:
+
+@itemize @bullet
+
+@item
+The mail-fetching functions have changed. See the manual for the
+many details. In particular, all procmail fetching variables are gone.
+
+If you used procmail like in
+
+@lisp
+(setq nnmail-use-procmail t)
+(setq nnmail-spool-file 'procmail)
+(setq nnmail-procmail-directory "~/mail/incoming/")
+(setq nnmail-procmail-suffix "\\.in")
+@end lisp
+
+this now has changed to
+
+@lisp
+(setq mail-sources
+ '((directory :path "~/mail/incoming/"
+ :suffix ".in")))
+@end lisp
+
+@xref{Mail Source Specifiers}.
+
+@item
+Gnus is now a @acronym{MIME}-capable reader. This affects many parts of
+Gnus, and adds a slew of new commands. See the manual for details.
+
+@item
+Gnus has also been multilingualized. This also affects too
+many parts of Gnus to summarize here, and adds many new variables.
+
+@item
+@code{gnus-auto-select-first} can now be a function to be
+called to position point.
+
+@item
+The user can now decide which extra headers should be included in
+summary buffers and @acronym{NOV} files.
+
+@item
+@code{gnus-article-display-hook} has been removed. Instead, a number
+of variables starting with @code{gnus-treat-} have been added.
+
+@item
+The Gnus posting styles have been redone again and now works in a
+subtly different manner.
+
+@item
+New web-based back ends have been added: @code{nnslashdot},
+@code{nnwarchive} and @code{nnultimate}. nnweb has been revamped,
+again, to keep up with ever-changing layouts.
+
+@item
+Gnus can now read @acronym{IMAP} mail via @code{nnimap}.
+
+@end itemize
+
+@node Oort Gnus
+@subsubsection Oort Gnus
+@cindex Oort Gnus
+
+New features in Gnus 5.10:
+
+@itemize @bullet
+
+@item Installation changes
+@c ***********************
+
+@itemize @bullet
+@item
+Upgrading from previous (stable) version if you have used Oort.
+
+If you have tried Oort (the unstable Gnus branch leading to this
+release) but went back to a stable version, be careful when upgrading to
+this version. In particular, you will probably want to remove all
+@file{.marks} (nnml) and @file{.mrk} (nnfolder) files, so that flags are
+read from your @file{.newsrc.eld} instead of from the
+@file{.marks}/@file{.mrk} file where this release store flags. See a
+later entry for more information about marks. Note that downgrading
+isn't save in general.
+
+@item
+Lisp files are now installed in @file{.../site-lisp/gnus/} by default.
+It defaulted to @file{.../site-lisp/} formerly. In addition to this,
+the new installer issues a warning if other Gnus installations which
+will shadow the latest one are detected. You can then remove those
+shadows manually or remove them using @code{make
+remove-installed-shadows}.
+
+@item
+New @file{make.bat} for compiling and installing Gnus under MS Windows
+
+Use @file{make.bat} if you want to install Gnus under MS Windows, the
+first argument to the batch-program should be the directory where
+@file{xemacs.exe} respectively @file{emacs.exe} is located, if you want
+to install Gnus after compiling it, give @file{make.bat} @code{/copy} as
+the second parameter.
+
+@file{make.bat} has been rewritten from scratch, it now features
+automatic recognition of XEmacs and Emacs, generates
+@file{gnus-load.el}, checks if errors occur while compilation and
+generation of info files and reports them at the end of the build
+process. It now uses @code{makeinfo} if it is available and falls
+back to @file{infohack.el} otherwise. @file{make.bat} should now
+install all files which are necessary to run Gnus and be generally a
+complete replacement for the @code{configure; make; make install}
+cycle used under Unix systems.
+
+The new @file{make.bat} makes @file{make-x.bat} and @file{xemacs.mak}
+superfluous, so they have been removed.
+
+@item
+@file{~/News/overview/} not used.
+
+As a result of the following change, the @file{~/News/overview/}
+directory is not used any more. You can safely delete the entire
+hierarchy.
+
+@c FIXME: 'gnus-load' is mentioned in README, which is not included in
+@c the repository. We should find a better place for this item.
+@item
+@code{(require 'gnus-load)}
+
+If you use a stand-alone Gnus distribution, you'd better add
+@code{(require 'gnus-load)} into your @file{~/.emacs} after adding the Gnus
+lisp directory into load-path.
+
+File @file{gnus-load.el} contains autoload commands, functions and variables,
+some of which may not be included in distributions of Emacsen.
+
+@end itemize
+
+@item New packages and libraries within Gnus
+@c *****************************************
+
+@itemize @bullet
+
+@item
+The revised Gnus @acronym{FAQ} is included in the manual,
+@xref{Frequently Asked Questions}.
+
+@item
+@acronym{TLS} wrapper shipped with Gnus
+
+@acronym{TLS}/@acronym{SSL} is now supported in @acronym{IMAP} and
+@acronym{NNTP} via @file{tls.el} and GnuTLS.
+
+@item
+Improved anti-spam features.
+
+Gnus is now able to take out spam from your mail and news streams
+using a wide variety of programs and filter rules. Among the supported
+methods are RBL blocklists, bogofilter and white/blacklists. Hooks
+for easy use of external packages such as SpamAssassin and Hashcash
+are also new. @ref{Thwarting Email Spam} and @ref{Spam Package}.
+@c FIXME: @xref{Spam Package}?. Should this be under Misc?
+
+@item
+Gnus supports server-side mail filtering using Sieve.
+
+Sieve rules can be added as Group Parameters for groups, and the
+complete Sieve script is generated using @kbd{D g} from the Group
+buffer, and then uploaded to the server using @kbd{C-c C-l} in the
+generated Sieve buffer. @xref{Sieve Commands}, and the new Sieve
+manual @ref{Top, , Top, sieve, Emacs Sieve}.
+
+@end itemize
+
+@item Changes in group mode
+@c ************************
+
+@itemize @bullet
+
+@item
+@code{gnus-group-read-ephemeral-group} can be called interactively,
+using @kbd{G M}.
+
+@item
+Retrieval of charters and control messages
+
+There are new commands for fetching newsgroup charters (@kbd{H c}) and
+control messages (@kbd{H C}).
+
+@item
+The new variable @code{gnus-parameters} can be used to set group parameters.
+
+Earlier this was done only via @kbd{G p} (or @kbd{G c}), which stored
+the parameters in @file{~/.newsrc.eld}, but via this variable you can
+enjoy the powers of customize, and simplified backups since you set the
+variable in @file{~/.gnus.el} instead of @file{~/.newsrc.eld}. The
+variable maps regular expressions matching group names to group
+parameters, a'la:
+@lisp
+(setq gnus-parameters
+ '(("mail\\..*"
+ (gnus-show-threads nil)
+ (gnus-use-scoring nil))
+ ("^nnimap:\\(foo.bar\\)$"
+ (to-group . "\\1"))))
+@end lisp
+
+@item
+Unread count correct in nnimap groups.
+
+The estimated number of unread articles in the group buffer should now
+be correct for nnimap groups. This is achieved by calling
+@code{nnimap-fixup-unread-after-getting-new-news} from the
+@code{gnus-setup-news-hook} (called on startup) and
+@code{gnus-after-getting-new-news-hook} (called after getting new
+mail). If you have modified those variables from the default, you may
+want to add @code{nnimap-fixup-unread-after-getting-new-news} again. If
+you were happy with the estimate and want to save some (minimal) time
+when getting new mail, remove the function.
+
+@item
+Group names are treated as UTF-8 by default.
+
+This is supposedly what USEFOR wanted to migrate to. See
+@code{gnus-group-name-charset-group-alist} and
+@code{gnus-group-name-charset-method-alist} for customization.
+
+@item
+@code{gnus-group-charset-alist} and
+@code{gnus-group-ignored-charsets-alist}.
+
+The regexps in these variables are compared with full group names
+instead of real group names in 5.8. Users who customize these
+variables should change those regexps accordingly. For example:
+@lisp
+("^han\\>" euc-kr) -> ("\\(^\\|:\\)han\\>" euc-kr)
+@end lisp
+
+@item
+Old intermediate incoming mail files (@file{Incoming*}) are deleted
+after a couple of days, not immediately. @xref{Mail Source
+Customization}. (New in Gnus 5.10.10 / Emacs 22.2)
+
+@end itemize
+
+@item Changes in summary and article mode
+@c **************************************
+
+@itemize @bullet
+
+@item
+@kbd{F} (@code{gnus-article-followup-with-original}) and @kbd{R}
+(@code{gnus-article-reply-with-original}) only yank the text in the
+region if the region is active.
+
+@item
+In draft groups, @kbd{e} is now bound to @code{gnus-draft-edit-message}.
+Use @kbd{B w} for @code{gnus-summary-edit-article} instead.
+
+@item
+Article Buttons
+
+More buttons for URLs, mail addresses, Message-IDs, Info links, man
+pages and Emacs or Gnus related references. @xref{Article Buttons}. The
+variables @code{gnus-button-@var{*}-level} can be used to control the
+appearance of all article buttons. @xref{Article Button Levels}.
+
+@item
+Single-part yenc encoded attachments can be decoded.
+
+@item
+Picons
+
+The picons code has been reimplemented to work in GNU Emacs---some of
+the previous options have been removed or renamed.
+
+Picons are small ``personal icons'' representing users, domain and
+newsgroups, which can be displayed in the Article buffer.
+@xref{Picons}.
+
+@item
+If the new option @code{gnus-treat-body-boundary} is non-@code{nil}, a
+boundary line is drawn at the end of the headers.
+
+@item
+Signed article headers (X-PGP-Sig) can be verified with @kbd{W p}.
+
+@item
+The Summary Buffer uses an arrow in the fringe to indicate the current
+article. Use @code{(setq gnus-summary-display-arrow nil)} to disable it.
+
+@item
+Warn about email replies to news
+
+Do you often find yourself replying to news by email by mistake? Then
+the new option @code{gnus-confirm-mail-reply-to-news} is just the thing for
+you.
+
+@item
+If the new option @code{gnus-summary-display-while-building} is
+non-@code{nil}, the summary buffer is shown and updated as it's being
+built.
+
+@item
+Gnus supports RFC 2369 mailing list headers, and adds a number of
+related commands in mailing list groups. @xref{Mailing List}.
+
+@item
+The Date header can be displayed in a format that can be read aloud
+in English. @xref{Article Date}.
+
+@item
+diffs are automatically highlighted in groups matching
+@code{mm-uu-diff-groups-regexp}
+
+@item
+Better handling of Microsoft citation styles
+
+Gnus now tries to recognize the mangled header block that some Microsoft
+mailers use to indicate that the rest of the message is a citation, even
+though it is not quoted in any way. The variable
+@code{gnus-cite-unsightly-citation-regexp} matches the start of these
+citations.
+
+The new command @kbd{W Y f}
+(@code{gnus-article-outlook-deuglify-article}) allows deuglifying broken
+Outlook (Express) articles.
+
+@item
+@code{gnus-article-skip-boring}
+
+If you set @code{gnus-article-skip-boring} to @code{t}, then Gnus will
+not scroll down to show you a page that contains only boring text,
+which by default means cited text and signature. You can customize
+what is skippable using @code{gnus-article-boring-faces}.
+
+This feature is especially useful if you read many articles that
+consist of a little new content at the top with a long, untrimmed
+message cited below.
+
+@item
+Smileys (@samp{:-)}, @samp{;-)} etc.)@: are now displayed graphically in
+Emacs too.
+
+Put @code{(setq gnus-treat-display-smileys nil)} in @file{~/.gnus.el} to
+disable it.
+
+@item
+Face headers handling. @xref{Face}.
+
+@item
+In the summary buffer, the new command @kbd{/ N} inserts new messages
+and @kbd{/ o} inserts old messages.
+
+@item
+Gnus decodes morse encoded messages if you press @kbd{W m}.
+
+@item
+@code{gnus-summary-line-format}
+
+The default value changed to @samp{%U%R%z%I%(%[%4L: %-23,23f%]%)
+%s\n}. Moreover @code{gnus-extra-headers},
+@code{nnmail-extra-headers} and @code{gnus-ignored-from-addresses}
+changed their default so that the users name will be replaced by the
+recipient's name or the group name posting to for @acronym{NNTP}
+groups.
+
+@item
+Deleting of attachments.
+
+The command @code{gnus-mime-save-part-and-strip} (bound to @kbd{C-o}
+on @acronym{MIME} buttons) saves a part and replaces the part with an
+external one. @code{gnus-mime-delete-part} (bound to @kbd{d} on
+@acronym{MIME} buttons) removes a part. It works only on back ends
+that support editing.
+
+@item
+@code{gnus-default-charset}
+
+The default value is determined from the
+@code{current-language-environment} variable, instead of
+@code{iso-8859-1}. Also the @samp{.*} item in
+@code{gnus-group-charset-alist} is removed.
+
+@item
+Printing capabilities are enhanced.
+
+Gnus supports Muttprint natively with @kbd{O P} from the Summary and
+Article buffers. Also, each individual @acronym{MIME} part can be
+printed using @kbd{p} on the @acronym{MIME} button.
+
+@item
+Extended format specs.
+
+Format spec @samp{%&user-date;} is added into
+@code{gnus-summary-line-format-alist}. Also, user defined extended
+format specs are supported. The extended format specs look like
+@samp{%u&foo;}, which invokes function
+@code{gnus-user-format-function-@var{foo}}. Because @samp{&} is used as the
+escape character, old user defined format @samp{%u&} is no longer supported.
+
+@item
+@kbd{/ *} (@code{gnus-summary-limit-include-cached}) is rewritten.
+@c FIXME: Was this a user-visible change?
+
+It was aliased to @kbd{Y c}
+(@code{gnus-summary-insert-cached-articles}). The new function filters
+out other articles.
+
+@item
+Some limiting commands accept a @kbd{C-u} prefix to negate the match.
+
+If @kbd{C-u} is used on subject, author or extra headers, i.e., @kbd{/
+s}, @kbd{/ a}, and @kbd{/ x}
+(@code{gnus-summary-limit-to-@{subject,author,extra@}}) respectively, the
+result will be to display all articles that do not match the expression.
+
+@item
+Gnus inlines external parts (message/external).
+
+@end itemize
+
+@item Changes in Message mode and related Gnus features
+@c ****************************************************
+
+@itemize @bullet
+
+@item
+Delayed articles
+
+You can delay the sending of a message with @kbd{C-c C-j} in the Message
+buffer. The messages are delivered at specified time. This is useful
+for sending yourself reminders. @xref{Delayed Articles}.
+
+@item
+If the new option @code{nnml-use-compressed-files} is non-@code{nil},
+the nnml back end allows compressed message files.
+
+@item
+The new option @code{gnus-gcc-mark-as-read} automatically marks
+Gcc articles as read.
+
+@item
+Externalizing of attachments
+
+If @code{gnus-gcc-externalize-attachments} or
+@code{message-fcc-externalize-attachments} is non-@code{nil}, attach
+local files as external parts.
+
+@item
+The envelope sender address can be customized when using Sendmail.
+@xref{Mail Variables, Mail Variables,, message, Message Manual}.
+
+@item
+Gnus no longer generate the Sender: header automatically.
+
+Earlier it was generated when the user configurable email address was
+different from the Gnus guessed default user address. As the guessing
+algorithm is rarely correct these days, and (more controversially) the
+only use of the Sender: header was to check if you are entitled to
+cancel/supersede news (which is now solved by Cancel Locks instead,
+see another entry), generation of the header has been disabled by
+default. See the variables @code{message-required-headers},
+@code{message-required-news-headers}, and
+@code{message-required-mail-headers}.
+
+@item
+Features from third party @file{message-utils.el} added to @file{message.el}.
+
+Message now asks if you wish to remove @samp{(was: <old subject>)} from
+subject lines (see @code{message-subject-trailing-was-query}). @kbd{C-c
+M-m} and @kbd{C-c M-f} inserts markers indicating included text.
+@kbd{C-c C-f a} adds a X-No-Archive: header. @kbd{C-c C-f x} inserts
+appropriate headers and a note in the body for cross-postings and
+followups (see the variables @code{message-cross-post-@var{*}}).
+
+@item
+References and X-Draft-From headers are no longer generated when you
+start composing messages and @code{message-generate-headers-first} is
+@code{nil}.
+
+@item
+Easy inclusion of X-Faces headers. @xref{X-Face}.
+
+@item
+Group Carbon Copy (GCC) quoting
+
+To support groups that contains SPC and other weird characters, groups
+are quoted before they are placed in the Gcc: header. This means
+variables such as @code{gnus-message-archive-group} should no longer
+contain quote characters to make groups containing SPC work. Also, if
+you are using the string @samp{nnml:foo, nnml:bar} (indicating Gcc
+into two groups) you must change it to return the list
+@code{("nnml:foo" "nnml:bar")}, otherwise the Gcc: line will be quoted
+incorrectly. Note that returning the string @samp{nnml:foo, nnml:bar}
+was incorrect earlier, it just didn't generate any problems since it
+was inserted directly.
+
+@item
+@code{message-insinuate-rmail}
+
+@c FIXME should that not be 'message-user-agent?
+Adding @code{(message-insinuate-rmail)} and @code{(setq
+mail-user-agent 'gnus-user-agent)} in @file{.emacs} convinces Rmail to
+compose, reply and forward messages in message-mode, where you can
+enjoy the power of @acronym{MML}.
+
+@item
+@code{message-minibuffer-local-map}
+
+The line below enables BBDB in resending a message:
+@lisp
+(define-key message-minibuffer-local-map [(tab)]
+ 'bbdb-complete-name)
+@end lisp
+
+@item
+@code{gnus-posting-styles}
+
+Add a new format of match like
+@lisp
+((header "to" "larsi.*org")
+ (Organization "Somewhere, Inc."))
+@end lisp
+The old format like the lines below is obsolete, but still accepted.
+@lisp
+(header "to" "larsi.*org"
+ (Organization "Somewhere, Inc."))
+@end lisp
+
+@item
+@code{message-ignored-news-headers} and @code{message-ignored-mail-headers}
+
+@samp{X-Draft-From} and @samp{X-Gnus-Agent-Meta-Information} have been
+added into these two variables. If you customized those, perhaps you
+need add those two headers too.
+
+@item
+Gnus supports the ``format=flowed'' (RFC 2646) parameter. On
+composing messages, it is enabled by @code{use-hard-newlines}.
+Decoding format=flowed was present but not documented in earlier
+versions.
+
+@item
+The option @code{mm-fill-flowed} can be used to disable treatment of
+``format=flowed'' messages. Also, flowed text is disabled when sending
+inline PGP signed messages. @xref{Flowed text, , Flowed text,
+emacs-mime, The Emacs MIME Manual}. (New in Gnus 5.10.7)
+@c This entry is also present in the node "No Gnus".
+
+@item
+Gnus supports the generation of RFC 2298 Disposition Notification requests.
+
+This is invoked with the @kbd{C-c M-n} key binding from message mode.
+
+@item
+Message supports the Importance: (RFC 2156) header.
+
+In the message buffer, @kbd{C-c C-f C-i} or @kbd{C-c C-u} cycles through
+the valid values.
+
+@item
+Gnus supports Cancel Locks in News.
+
+This means a header @samp{Cancel-Lock} is inserted in news posting. It is
+used to determine if you wrote an article or not (for canceling and
+superseding). Gnus generates a random password string the first time
+you post a message, and saves it in your @file{~/.emacs} using the Custom
+system. While the variable is called @code{canlock-password}, it is not
+security sensitive data. Publishing your canlock string on the web
+will not allow anyone to be able to anything she could not already do.
+The behavior can be changed by customizing @code{message-insert-canlock}.
+
+@item
+Gnus supports @acronym{PGP} (RFC 1991/2440), @acronym{PGP/MIME} (RFC
+2015/3156) and @acronym{S/MIME} (RFC 2630--2633).
+
+It needs an external @acronym{S/MIME} and OpenPGP implementation, but no
+additional Lisp libraries. This add several menu items to the
+Attachments menu, and @kbd{C-c RET} key bindings, when composing
+messages. This also obsoletes @code{gnus-article-hide-pgp-hook}.
+
+@item
+@acronym{MML} (Mime compose) prefix changed from @kbd{M-m} to @kbd{C-c
+C-m}.
+
+This change was made to avoid conflict with the standard binding of
+@code{back-to-indentation}, which is also useful in message mode.
+
+@item
+The default for @code{message-forward-show-mml} changed to the symbol
+@code{best}.
+
+The behavior for the @code{best} value is to show @acronym{MML} (i.e.,
+convert to @acronym{MIME}) when appropriate. @acronym{MML} will not be
+used when forwarding signed or encrypted messages, as the conversion
+invalidate the digital signature.
+
+@item
+If @code{auto-compression-mode} is enabled, attachments are automatically
+decompressed when activated.
+@c FIXME: Does this affect article or message mode?
+
+@item
+Support for non-@acronym{ASCII} domain names
+
+Message supports non-@acronym{ASCII} domain names in From:, To: and
+Cc: and will query you whether to perform encoding when you try to
+send a message. The variable @code{message-use-idna} controls this.
+Gnus will also decode non-@acronym{ASCII} domain names in From:, To:
+and Cc: when you view a message. The variable @code{gnus-use-idna}
+controls this.
+
+@item You can now drag and drop attachments to the Message buffer.
+See @code{mml-dnd-protocol-alist} and @code{mml-dnd-attach-options}.
+@xref{MIME, ,MIME, message, Message Manual}.
+@c New in 5.10.9 / 5.11 (Emacs 22.1)
+
+@item @code{auto-fill-mode} is enabled by default in Message mode.
+See @code{message-fill-column}. @xref{Various Message Variables, ,
+Message Headers, message, Message Manual}.
+@c New in Gnus 5.10.12 / 5.11 (Emacs 22.3)
+
+@end itemize
+
+@item Changes in back ends
+@c ***********************
+
+@itemize @bullet
+@item
+Gnus can display RSS newsfeeds as a newsgroup. @xref{RSS}.
+
+@item
+The nndoc back end now supports mailman digests and exim bounces.
+
+@item
+Gnus supports Maildir groups.
+
+Gnus includes a new back end @file{nnmaildir.el}. @xref{Maildir}.
+
+@item
+The nnml and nnfolder back ends store marks for each groups.
+
+This makes it possible to take backup of nnml/nnfolder servers/groups
+separately of @file{~/.newsrc.eld}, while preserving marks. It also
+makes it possible to share articles and marks between users (without
+sharing the @file{~/.newsrc.eld} file) within, e.g., a department. It
+works by storing the marks stored in @file{~/.newsrc.eld} in a per-group
+file @file{.marks} (for nnml) and @file{@var{groupname}.mrk} (for
+nnfolder, named @var{groupname}). If the nnml/nnfolder is moved to
+another machine, Gnus will automatically use the @file{.marks} or
+@file{.mrk} file instead of the information in @file{~/.newsrc.eld}.
+The new server variables @code{nnml-marks-is-evil} and
+@code{nnfolder-marks-is-evil} can be used to disable this feature.
+
+@end itemize
+
+@item Appearance
+@c *************
+
+@itemize @bullet
+
+@item
+The menu bar item (in Group and Summary buffer) named ``Misc'' has
+been renamed to ``Gnus''.
+
+@item
+The menu bar item (in Message mode) named ``@acronym{MML}'' has been
+renamed to ``Attachments''. Note that this menu also contains security
+related stuff, like signing and encryption (@pxref{Security, Security,,
+message, Message Manual}).
+
+@item
+The tool bars have been updated to use GNOME icons in Group, Summary and
+Message mode. You can also customize the tool bars: @kbd{M-x
+customize-apropos RET -tool-bar$} should get you started. This is a new
+feature in Gnus 5.10.10. (Only for Emacs, not in XEmacs.)
+
+@item The tool bar icons are now (de)activated correctly
+in the group buffer, see the variable @code{gnus-group-update-tool-bar}.
+Its default value depends on your Emacs version. This is a new feature
+in Gnus 5.10.9.
+@end itemize
+
+
+@item Miscellaneous changes
+@c ************************
+
+@itemize @bullet
+
+@item
+@code{gnus-agent}
+
+The Gnus Agent has seen a major updated and is now enabled by default,
+and all nntp and nnimap servers from @code{gnus-select-method} and
+@code{gnus-secondary-select-method} are agentized by default. Earlier
+only the server in @code{gnus-select-method} was agentized by the
+default, and the agent was disabled by default. When the agent is
+enabled, headers are now also retrieved from the Agent cache instead
+of the back ends when possible. Earlier this only happened in the
+unplugged state. You can enroll or remove servers with @kbd{J a} and
+@kbd{J r} in the server buffer. Gnus will not download articles into
+the Agent cache, unless you instruct it to do so, though, by using
+@kbd{J u} or @kbd{J s} from the Group buffer. You revert to the old
+behavior of having the Agent disabled with @code{(setq gnus-agent
+nil)}. Note that putting @code{(gnus-agentize)} in @file{~/.gnus.el}
+is not needed any more.
+
+@item
+Gnus reads the @acronym{NOV} and articles in the Agent if plugged.
+
+If one reads an article while plugged, and the article already exists
+in the Agent, it won't get downloaded once more. @code{(setq
+gnus-agent-cache nil)} reverts to the old behavior.
+
+@item
+Dired integration
+
+@code{gnus-dired-minor-mode} (see @ref{Other modes}) installs key
+bindings in dired buffers to send a file as an attachment, open a file
+using the appropriate mailcap entry, and print a file using the mailcap
+entry.
+
+@item
+The format spec @code{%C} for positioning point has changed to @code{%*}.
+
+@item
+@code{gnus-slave-unplugged}
+
+A new command which starts Gnus offline in slave mode.
+
+@end itemize
+
+@end itemize
+
+@node No Gnus
+@subsubsection No Gnus
+@cindex No Gnus
+
+New features in No Gnus:
+@c FIXME: Gnus 5.12?
+
+@include gnus-news.texi
+
+@node Ma Gnus
+@subsubsection Ma Gnus
+@cindex Ma Gnus
+
+I'm sure there will be lots of text here. It's really spelled 真
+Gnus.
+
+New features in Ma Gnus:
+
+@itemize @bullet
+
+@item Installation changes
+@c ***********************
+
+@itemize @bullet
+@item
+Lisp source files and info files to be installed will be compressed by
+gzip by default.
+
+If you don't want those files to be compressed, use the configure option
+@samp{--without-compress-install}. Lisp source files that don't have
+the compiled elc version in the installation directory will not be
+compressed.
+
+@end itemize
+
+@item Changes in summary and article mode
+@c **************************************
+
+@itemize @bullet
+
+@item
+By default, @acronym{MIME} part buttons for attachments (if any) will
+appear in the end of the article header in addition to the bottom of the
+article body, so you can easily find them without scrolling the article
+again and again. @xref{MIME Commands}.
+
+@end itemize
+
+@item Changes in Message mode and related Gnus features
+@c ****************************************************
+
+@itemize @bullet
+
+@item
+The new hooks @code{gnus-gcc-pre-body-encode-hook} and
+@code{gnus-gcc-post-body-encode-hook} are run before/after encoding
+the message body of the Gcc copy of a sent message. See
+@xref{Archived Messages}.
+
+@end itemize
+
+@end itemize
+
+@iftex
+
+@page
+@node The Manual
+@section The Manual
+@cindex colophon
+@cindex manual
+
+This manual was generated from a TeXinfo file and then run through
+either @code{texi2dvi}
+@iflatex
+or my own home-brewed TeXinfo to \LaTeX\ transformer,
+and then run through @code{latex} and @code{dvips}
+@end iflatex
+to get what you hold in your hands now.
+
+The following conventions have been used:
+
+@enumerate
+
+@item
+This is a @samp{string}
+
+@item
+This is a @kbd{keystroke}
+
+@item
+This is a @file{file}
+
+@item
+This is a @code{symbol}
+
+@end enumerate
+
+So if I were to say ``set @code{flargnoze} to @samp{yes}'', that would
+mean:
+
+@lisp
+(setq flargnoze "yes")
+@end lisp
+
+If I say ``set @code{flumphel} to @code{yes}'', that would mean:
+
+@lisp
+(setq flumphel 'yes)
+@end lisp
+
+@samp{yes} and @code{yes} are two @emph{very} different things---don't
+ever get them confused.
+
+@iflatex
+@c @head
+Of course, everything in this manual is of vital interest, so you should
+read it all. Several times. However, if you feel like skimming the
+manual, look for that gnu head you should see in the margin over
+there---it means that what's being discussed is of more importance than
+the rest of the stuff. (On the other hand, if everything is infinitely
+important, how can anything be more important than that? Just one more
+of the mysteries of this world, I guess.)
+@end iflatex
+
+@end iftex
+
+
+@node On Writing Manuals
+@section On Writing Manuals
+
+I guess most manuals are written after-the-fact; documenting a program
+that's already there. This is not how this manual is written. When
+implementing something, I write the manual entry for that something
+straight away. I then see that it's difficult to explain the
+functionality, so I write how it's supposed to be, and then I change the
+implementation. Writing the documentation and writing the code go hand
+in hand.
+
+This, of course, means that this manual has no, or little, flow. It
+documents absolutely everything in Gnus, but often not where you're
+looking for it. It is a reference manual, and not a guide to how to get
+started with Gnus.
+
+That would be a totally different book, that should be written using the
+reference manual as source material. It would look quite different.
+
+
+@page
+@node Terminology
+@section Terminology
+
+@cindex terminology
+@table @dfn
+
+@item news
+@cindex news
+This is what you are supposed to use this thing for---reading news.
+News is generally fetched from a nearby @acronym{NNTP} server, and is
+generally publicly available to everybody. If you post news, the entire
+world is likely to read just what you have written, and they'll all
+snigger mischievously. Behind your back.
+
+@item mail
+@cindex mail
+Everything that's delivered to you personally is mail. Some news/mail
+readers (like Gnus) blur the distinction between mail and news, but
+there is a difference. Mail is private. News is public. Mailing is
+not posting, and replying is not following up.
+
+@item reply
+@cindex reply
+Send a mail to the person who has written what you are reading.
+
+@item follow up
+@cindex follow up
+Post an article to the current newsgroup responding to the article you
+are reading.
+
+@item back end
+@cindex back end
+Gnus considers mail and news to be mostly the same, really. The only
+difference is how to access the actual articles. News articles are
+commonly fetched via the protocol @acronym{NNTP}, whereas mail
+messages could be read from a file on the local disk. The internal
+architecture of Gnus thus comprises a ``front end'' and a number of
+``back ends''. Internally, when you enter a group (by hitting
+@key{RET}, say), you thereby invoke a function in the front end in
+Gnus. The front end then ``talks'' to a back end and says things like
+``Give me the list of articles in the foo group'' or ``Show me article
+number 4711''.
+
+So a back end mainly defines either a protocol (the @code{nntp} back
+end accesses news via @acronym{NNTP}, the @code{nnimap} back end
+accesses mail via @acronym{IMAP}) or a file format and directory
+layout (the @code{nnspool} back end accesses news via the common
+``spool directory'' format, the @code{nnml} back end access mail via a
+file format and directory layout that's quite similar).
+
+Gnus does not handle the underlying media, so to speak---this is all
+done by the back ends. A back end is a collection of functions to
+access the articles.
+
+However, sometimes the term ``back end'' is also used where ``server''
+would have been more appropriate. And then there is the term ``select
+method'' which can mean either. The Gnus terminology can be quite
+confusing.
+
+@item native
+@cindex native
+Gnus will always use one method (and back end) as the @dfn{native}, or
+default, way of getting news. Groups from the native select method
+have names like @samp{gnu.emacs.gnus}.
+
+@item foreign
+@cindex foreign
+You can also have any number of foreign groups active at the same
+time. These are groups that use non-native non-secondary back ends
+for getting news. Foreign groups have names like
+@samp{nntp+news.gmane.org:gmane.emacs.gnus.devel}.
+
+@item secondary
+@cindex secondary
+Secondary back ends are somewhere half-way between being native and
+being foreign, but they mostly act like they are native, but they, too
+have names like @samp{nntp+news.gmane.org:gmane.emacs.gnus.devel}.
+
+@item article
+@cindex article
+A message that has been posted as news.
+
+@item mail message
+@cindex mail message
+A message that has been mailed.
+
+@item message
+@cindex message
+A mail message or news article
+
+@item head
+@cindex head
+The top part of a message, where administrative information (etc.)@: is
+put.
+
+@item body
+@cindex body
+The rest of an article. Everything not in the head is in the
+body.
+
+@item header
+@cindex header
+A line from the head of an article.
+
+@item headers
+@cindex headers
+A collection of such lines, or a collection of heads. Or even a
+collection of @acronym{NOV} lines.
+
+@item @acronym{NOV}
+@cindex @acronym{NOV}
+@acronym{NOV} stands for News OverView, which is a type of news server
+header which provide datas containing the condensed header information
+of articles. They are produced by the server itself; in the @code{nntp}
+back end Gnus uses the ones that the @acronym{NNTP} server makes, but
+Gnus makes them by itself for some backends (in particular, @code{nnml}).
+
+When Gnus enters a group, it asks the back end for the headers of all
+unread articles in the group. Most servers support the News OverView
+format, which is more compact and much faster to read and parse than the
+normal @sc{head} format.
+
+The @acronym{NOV} data consist of one or more text lines (@pxref{Text
+Lines, ,Motion by Text Lines, elisp, The Emacs Lisp Reference Manual})
+where each line has the header information of one article. The header
+information is a tab-separated series of the header's contents including
+an article number, a subject, an author, a date, a message-id,
+references, etc.
+
+Those data enable Gnus to generate summary lines quickly. However, if
+the server does not support @acronym{NOV} or you disable it purposely or
+for some reason, Gnus will try to generate the header information by
+parsing each article's headers one by one. It will take time.
+Therefore, it is not usually a good idea to set nn*-nov-is-evil
+(@pxref{Slow/Expensive Connection}) to a non-@code{nil} value unless you
+know that the server makes wrong @acronym{NOV} data.
+
+@item level
+@cindex levels
+Each group is subscribed at some @dfn{level} or other (1--9). The ones
+that have a lower level are ``more'' subscribed than the groups with a
+higher level. In fact, groups on levels 1--5 are considered
+@dfn{subscribed}; 6--7 are @dfn{unsubscribed}; 8 are @dfn{zombies}; and 9
+are @dfn{killed}. Commands for listing groups and scanning for new
+articles will all use the numeric prefix as @dfn{working level}.
+
+@item killed groups
+@cindex killed groups
+No information on killed groups is stored or updated, which makes killed
+groups much easier to handle than subscribed groups.
+
+@item zombie groups
+@cindex zombie groups
+Just like killed groups, only slightly less dead.
+
+@item active file
+@cindex active file
+The news server has to keep track of what articles it carries, and what
+groups exist. All this information in stored in the active file, which
+is rather large, as you might surmise.
+
+@item bogus groups
+@cindex bogus groups
+A group that exists in the @file{.newsrc} file, but isn't known to the
+server (i.e., it isn't in the active file), is a @emph{bogus group}.
+This means that the group probably doesn't exist (any more).
+
+@item activating
+@cindex activating groups
+The act of asking the server for info on a group and computing the
+number of unread articles is called @dfn{activating the group}.
+Un-activated groups are listed with @samp{*} in the group buffer.
+
+@item spool
+@cindex spool
+News servers store their articles locally in one fashion or other.
+One old-fashioned storage method is to have just one file per
+article. That's called a ``traditional spool''.
+
+@item server
+@cindex server
+A machine one can connect to and get news (or mail) from.
+
+@item select method
+@cindex select method
+A structure that specifies the back end, the server and the virtual
+server settings.
+
+@item virtual server
+@cindex virtual server
+A named select method. Since a select method defines all there is to
+know about connecting to a (physical) server, taking the thing as a
+whole is a virtual server.
+
+@item washing
+@cindex washing
+Taking a buffer and running it through a filter of some sort. The
+result will (more often than not) be cleaner and more pleasing than the
+original.
+
+@item ephemeral groups
+@cindex ephemeral groups
+@cindex temporary groups
+Most groups store data on what articles you have read. @dfn{Ephemeral}
+groups are groups that will have no data stored---when you exit the
+group, it'll disappear into the aether.
+
+@item solid groups
+@cindex solid groups
+This is the opposite of ephemeral groups. All groups listed in the
+group buffer are solid groups.
+
+@item sparse articles
+@cindex sparse articles
+These are article placeholders shown in the summary buffer when
+@code{gnus-build-sparse-threads} has been switched on.
+
+@item threading
+@cindex threading
+To put responses to articles directly after the articles they respond
+to---in a hierarchical fashion.
+
+@item root
+@cindex root
+@cindex thread root
+The first article in a thread is the root. It is the ancestor of all
+articles in the thread.
+
+@item parent
+@cindex parent
+An article that has responses.
+
+@item child
+@cindex child
+An article that responds to a different article---its parent.
+
+@item digest
+@cindex digest
+A collection of messages in one file. The most common digest format is
+specified by RFC 1153.
+
+@item splitting
+@cindex splitting, terminology
+@cindex mail sorting
+@cindex mail filtering (splitting)
+The action of sorting your emails according to certain rules. Sometimes
+incorrectly called mail filtering.
+
+@end table
+
+
+@page
+@node Customization
+@section Customization
+@cindex general customization
+
+All variables are properly documented elsewhere in this manual. This
+section is designed to give general pointers on how to customize Gnus
+for some quite common situations.
+
+@menu
+* Slow/Expensive Connection:: You run a local Emacs and get the news elsewhere.
+* Slow Terminal Connection:: You run a remote Emacs.
+* Little Disk Space:: You feel that having large setup files is icky.
+* Slow Machine:: You feel like buying a faster machine.
+@end menu
+
+
+@node Slow/Expensive Connection
+@subsection Slow/Expensive Connection
+
+If you run Emacs on a machine locally, and get your news from a machine
+over some very thin strings, you want to cut down on the amount of data
+Gnus has to get from the server.
+
+@table @code
+
+@item gnus-read-active-file
+Set this to @code{nil}, which will inhibit Gnus from requesting the
+entire active file from the server. This file is often very large. You
+also have to set @code{gnus-check-new-newsgroups} and
+@code{gnus-check-bogus-newsgroups} to @code{nil} to make sure that Gnus
+doesn't suddenly decide to fetch the active file anyway.
+
+@item gnus-nov-is-evil
+@vindex gnus-nov-is-evil
+Usually this one must @emph{always} be @code{nil} (which is the
+default). If, for example, you wish to not use @acronym{NOV}
+(@pxref{Terminology}) with the @code{nntp} back end (@pxref{Crosspost
+Handling}), set @code{nntp-nov-is-evil} to a non-@code{nil} value
+instead of setting this. But you normally do not need to set
+@code{nntp-nov-is-evil} since Gnus by itself will detect whether the
+@acronym{NNTP} server supports @acronym{NOV}. Anyway, grabbing article
+headers from the @acronym{NNTP} server will not be very fast if you tell
+Gnus not to use @acronym{NOV}.
+
+As the variables for the other back ends, there are
+@code{nndiary-nov-is-evil}, @code{nndir-nov-is-evil},
+@code{nnfolder-nov-is-evil}, @code{nnimap-nov-is-evil},
+@code{nnml-nov-is-evil}, and @code{nnspool-nov-is-evil}. Note that a
+non-@code{nil} value for @code{gnus-nov-is-evil} overrides all those
+variables.
+@end table
+
+
+@node Slow Terminal Connection
+@subsection Slow Terminal Connection
+
+Let's say you use your home computer for dialing up the system that runs
+Emacs and Gnus. If your modem is slow, you want to reduce (as much as
+possible) the amount of data sent over the wires.
+
+@table @code
+
+@item gnus-auto-center-summary
+Set this to @code{nil} to inhibit Gnus from re-centering the summary
+buffer all the time. If it is @code{vertical}, do only vertical
+re-centering. If it is neither @code{nil} nor @code{vertical}, do both
+horizontal and vertical recentering.
+
+@item gnus-visible-headers
+Cut down on the headers included in the articles to the
+minimum. You can, in fact, make do without them altogether---most of the
+useful data is in the summary buffer, anyway. Set this variable to
+@samp{^NEVVVVER} or @samp{From:}, or whatever you feel you need.
+
+Use the following to enable all the available hiding features:
+@lisp
+(setq gnus-treat-hide-headers 'head
+ gnus-treat-hide-signature t
+ gnus-treat-hide-citation t)
+@end lisp
+
+@item gnus-use-full-window
+By setting this to @code{nil}, you can make all the windows smaller.
+While this doesn't really cut down much generally, it means that you
+have to see smaller portions of articles before deciding that you didn't
+want to read them anyway.
+
+@item gnus-thread-hide-subtree
+If this is non-@code{nil}, all threads in the summary buffer will be
+hidden initially.
+
+
+@item gnus-updated-mode-lines
+If this is @code{nil}, Gnus will not put information in the buffer mode
+lines, which might save some time.
+@end table
+
+
+@node Little Disk Space
+@subsection Little Disk Space
+@cindex disk space
+
+The startup files can get rather large, so you may want to cut their
+sizes a bit if you are running out of space.
+
+@table @code
+
+@item gnus-save-newsrc-file
+If this is @code{nil}, Gnus will never save @file{.newsrc}---it will
+only save @file{.newsrc.eld}. This means that you will not be able to
+use any other newsreaders than Gnus. This variable is @code{t} by
+default.
+
+@item gnus-read-newsrc-file
+If this is @code{nil}, Gnus will never read @file{.newsrc}---it will
+only read @file{.newsrc.eld}. This means that you will not be able to
+use any other newsreaders than Gnus. This variable is @code{t} by
+default.
+
+@item gnus-save-killed-list
+If this is @code{nil}, Gnus will not save the list of dead groups. You
+should also set @code{gnus-check-new-newsgroups} to @code{ask-server}
+and @code{gnus-check-bogus-newsgroups} to @code{nil} if you set this
+variable to @code{nil}. This variable is @code{t} by default.
+
+@end table
+
+
+@node Slow Machine
+@subsection Slow Machine
+@cindex slow machine
+
+If you have a slow machine, or are just really impatient, there are a
+few things you can do to make Gnus run faster.
+
+Set @code{gnus-check-new-newsgroups} and
+@code{gnus-check-bogus-newsgroups} to @code{nil} to make startup faster.
+
+Set @code{gnus-show-threads}, @code{gnus-use-cross-reference} and
+@code{gnus-nov-is-evil} to @code{nil} to make entering and exiting the
+summary buffer faster. Also @pxref{Slow/Expensive Connection}.
+
+
+@page
+@node Troubleshooting
+@section Troubleshooting
+@cindex troubleshooting
+
+Gnus works @emph{so} well straight out of the box---I can't imagine any
+problems, really.
+
+Ahem.
+
+@enumerate
+
+@item
+Make sure your computer is switched on.
+
+@item
+Make sure that you really load the current Gnus version. If you have
+been running @sc{gnus}, you need to exit Emacs and start it up again before
+Gnus will work.
+
+@item
+Try doing an @kbd{M-x gnus-version}. If you get something that looks
+like @c
+@samp{Ma Gnus v0.14} @c Adjust ../Makefile.in if you change this line!
+@c
+you have the right files loaded. Otherwise you have some old @file{.el}
+files lying around. Delete these.
+
+@item
+Read the help group (@kbd{G h} in the group buffer) for a
+@acronym{FAQ} and a how-to.
+
+@item
+@vindex max-lisp-eval-depth
+Gnus works on many recursive structures, and in some extreme (and very
+rare) cases Gnus may recurse down ``too deeply'' and Emacs will beep at
+you. If this happens to you, set @code{max-lisp-eval-depth} to 500 or
+something like that.
+@end enumerate
+
+If all else fails, report the problem as a bug.
+
+@cindex bugs
+@cindex reporting bugs
+
+@kindex M-x gnus-bug
+@findex gnus-bug
+If you find a bug in Gnus, you can report it with the @kbd{M-x gnus-bug}
+command. @kbd{M-x set-variable RET debug-on-error RET t RET}, and send
+me the backtrace. I will fix bugs, but I can only fix them if you send
+me a precise description as to how to reproduce the bug.
+
+You really can never be too detailed in a bug report. Always use the
+@kbd{M-x gnus-bug} command when you make bug reports, even if it creates
+a 10Kb mail each time you use it, and even if you have sent me your
+environment 500 times before. I don't care. I want the full info each
+time.
+
+It is also important to remember that I have no memory whatsoever. If
+you send a bug report, and I send you a reply, and then you just send
+back ``No, it's not! Moron!'', I will have no idea what you are
+insulting me about. Always over-explain everything. It's much easier
+for all of us---if I don't have all the information I need, I will just
+mail you and ask for more info, and everything takes more time.
+
+If the problem you're seeing is very visual, and you can't quite explain
+it, copy the Emacs window to a file (with @code{xwd}, for instance), put
+it somewhere it can be reached, and include the URL of the picture in
+the bug report.
+
+@cindex patches
+If you would like to contribute a patch to fix bugs or make
+improvements, please produce the patch using @samp{diff -u}.
+
+@cindex edebug
+If you want to debug your problem further before reporting, possibly
+in order to solve the problem yourself and send a patch, you can use
+edebug. Debugging Lisp code is documented in the Elisp manual
+(@pxref{Debugging, , Debugging Lisp Programs, elisp, The GNU Emacs
+Lisp Reference Manual}). To get you started with edebug, consider if
+you discover some weird behavior when pressing @kbd{c}, the first
+step is to do @kbd{C-h k c} and click on the hyperlink (Emacs only) in
+the documentation buffer that leads you to the function definition,
+then press @kbd{M-x edebug-defun RET} with point inside that function,
+return to Gnus and press @kbd{c} to invoke the code. You will be
+placed in the lisp buffer and can single step using @kbd{SPC} and
+evaluate expressions using @kbd{M-:} or inspect variables using
+@kbd{C-h v}, abort execution with @kbd{q}, and resume execution with
+@kbd{c} or @kbd{g}.
+
+@cindex elp
+@cindex profile
+@cindex slow
+Sometimes, a problem do not directly generate an elisp error but
+manifests itself by causing Gnus to be very slow. In these cases, you
+can use @kbd{M-x toggle-debug-on-quit} and press @kbd{C-g} when things are
+slow, and then try to analyze the backtrace (repeating the procedure
+helps isolating the real problem areas).
+
+A fancier approach is to use the elisp profiler, ELP@. The profiler is
+(or should be) fully documented elsewhere, but to get you started
+there are a few steps that need to be followed. First, instrument the
+part of Gnus you are interested in for profiling, e.g., @kbd{M-x
+elp-instrument-package RET gnus} or @kbd{M-x elp-instrument-package
+RET message}. Then perform the operation that is slow and press
+@kbd{M-x elp-results}. You will then see which operations that takes
+time, and can debug them further. If the entire operation takes much
+longer than the time spent in the slowest function in the profiler
+output, you probably profiled the wrong part of Gnus. To reset
+profiling statistics, use @kbd{M-x elp-reset-all}. @kbd{M-x
+elp-restore-all} is supposed to remove profiling, but given the
+complexities and dynamic code generation in Gnus, it might not always
+work perfectly.
+
+@cindex gnu.emacs.gnus
+@cindex ding mailing list
+If you just need help, you are better off asking on
+@samp{gnu.emacs.gnus}. I'm not very helpful. You can also ask on
+@email{ding@@gnus.org, the ding mailing list}. Write to
+@email{ding-request@@gnus.org} to subscribe.
+
+
+@page
+@node Gnus Reference Guide
+@section Gnus Reference Guide
+
+It is my hope that other people will figure out smart stuff that Gnus
+can do, and that other people will write those smart things as well. To
+facilitate that I thought it would be a good idea to describe the inner
+workings of Gnus. And some of the not-so-inner workings, while I'm at
+it.
+
+You can never expect the internals of a program not to change, but I
+will be defining (in some details) the interface between Gnus and its
+back ends (this is written in stone), the format of the score files
+(ditto), data structures (some are less likely to change than others)
+and general methods of operation.
+
+@menu
+* Gnus Utility Functions:: Common functions and variable to use.
+* Back End Interface:: How Gnus communicates with the servers.
+* Score File Syntax:: A BNF definition of the score file standard.
+* Headers:: How Gnus stores headers internally.
+* Ranges:: A handy format for storing mucho numbers.
+* Group Info:: The group info format.
+* Extended Interactive:: Symbolic prefixes and stuff.
+* Emacs/XEmacs Code:: Gnus can be run under all modern Emacsen.
+* Various File Formats:: Formats of files that Gnus use.
+@end menu
+
+
+@node Gnus Utility Functions
+@subsection Gnus Utility Functions
+@cindex Gnus utility functions
+@cindex utility functions
+@cindex functions
+@cindex internal variables
+
+When writing small functions to be run from hooks (and stuff), it's
+vital to have access to the Gnus internal functions and variables.
+Below is a list of the most common ones.
+
+@table @code
+
+@item gnus-newsgroup-name
+@vindex gnus-newsgroup-name
+This variable holds the name of the current newsgroup.
+
+@item gnus-find-method-for-group
+@findex gnus-find-method-for-group
+A function that returns the select method for @var{group}.
+
+@item gnus-group-real-name
+@findex gnus-group-real-name
+Takes a full (prefixed) Gnus group name, and returns the unprefixed
+name.
+
+@item gnus-group-prefixed-name
+@findex gnus-group-prefixed-name
+Takes an unprefixed group name and a select method, and returns the full
+(prefixed) Gnus group name.
+
+@item gnus-get-info
+@findex gnus-get-info
+Returns the group info list for @var{group} (@pxref{Group Info}).
+
+@item gnus-group-unread
+@findex gnus-group-unread
+The number of unread articles in @var{group}, or @code{t} if that is
+unknown.
+
+@item gnus-active
+@findex gnus-active
+The active entry (i.e., a cons cell containing the lowest and highest
+article numbers) for @var{group}.
+
+@item gnus-set-active
+@findex gnus-set-active
+Set the active entry for @var{group}.
+
+@item gnus-add-current-to-buffer-list
+@findex gnus-add-current-to-buffer-list
+Adds the current buffer to the list of buffers to be killed on Gnus
+exit.
+
+@item gnus-continuum-version
+@findex gnus-continuum-version
+Takes a Gnus version string as a parameter and returns a floating point
+number. Earlier versions will always get a lower number than later
+versions.
+
+@item gnus-group-read-only-p
+@findex gnus-group-read-only-p
+Says whether @var{group} is read-only or not.
+
+@item gnus-news-group-p
+@findex gnus-news-group-p
+Says whether @var{group} came from a news back end.
+
+@item gnus-ephemeral-group-p
+@findex gnus-ephemeral-group-p
+Says whether @var{group} is ephemeral or not.
+
+@item gnus-server-to-method
+@findex gnus-server-to-method
+Returns the select method corresponding to @var{server}.
+
+@item gnus-server-equal
+@findex gnus-server-equal
+Says whether two virtual servers are essentially equal. For instance,
+two virtual servers may have server parameters in different order, but
+this function will consider them equal.
+
+@item gnus-group-native-p
+@findex gnus-group-native-p
+Says whether @var{group} is native or not.
+
+@item gnus-group-secondary-p
+@findex gnus-group-secondary-p
+Says whether @var{group} is secondary or not.
+
+@item gnus-group-foreign-p
+@findex gnus-group-foreign-p
+Says whether @var{group} is foreign or not.
+
+@item gnus-group-find-parameter
+@findex gnus-group-find-parameter
+Returns the parameter list of @var{group} (@pxref{Group Parameters}).
+If given a second parameter, returns the value of that parameter for
+@var{group}.
+
+@item gnus-group-set-parameter
+@findex gnus-group-set-parameter
+Takes three parameters; @var{group}, @var{parameter} and @var{value}.
+
+@item gnus-narrow-to-body
+@findex gnus-narrow-to-body
+Narrows the current buffer to the body of the article.
+
+@item gnus-check-backend-function
+@findex gnus-check-backend-function
+Takes two parameters, @var{function} and @var{group}. If the back end
+@var{group} comes from supports @var{function}, return non-@code{nil}.
+
+@lisp
+(gnus-check-backend-function "request-scan" "nnml:misc")
+@result{} t
+@end lisp
+
+@item gnus-read-method
+@findex gnus-read-method
+Prompts the user for a select method.
+
+@end table
+
+
+@node Back End Interface
+@subsection Back End Interface
+
+Gnus doesn't know anything about @acronym{NNTP}, spools, mail or virtual
+groups. It only knows how to talk to @dfn{virtual servers}. A virtual
+server is a @dfn{back end} and some @dfn{back end variables}. As examples
+of the first, we have @code{nntp}, @code{nnspool} and @code{nnmbox}. As
+examples of the latter we have @code{nntp-port-number} and
+@code{nnmbox-directory}.
+
+When Gnus asks for information from a back end---say @code{nntp}---on
+something, it will normally include a virtual server name in the
+function parameters. (If not, the back end should use the ``current''
+virtual server.) For instance, @code{nntp-request-list} takes a virtual
+server as its only (optional) parameter. If this virtual server hasn't
+been opened, the function should fail.
+
+Note that a virtual server name has no relation to some physical server
+name. Take this example:
+
+@lisp
+(nntp "odd-one"
+ (nntp-address "ifi.uio.no")
+ (nntp-port-number 4324))
+@end lisp
+
+Here the virtual server name is @samp{odd-one} while the name of
+the physical server is @samp{ifi.uio.no}.
+
+The back ends should be able to switch between several virtual servers.
+The standard back ends implement this by keeping an alist of virtual
+server environments that they pull down/push up when needed.
+
+There are two groups of interface functions: @dfn{required functions},
+which must be present, and @dfn{optional functions}, which Gnus will
+always check for presence before attempting to call 'em.
+
+All these functions are expected to return data in the buffer
+@code{nntp-server-buffer} (@samp{ *nntpd*}), which is somewhat
+unfortunately named, but we'll have to live with it. When I talk about
+@dfn{resulting data}, I always refer to the data in that buffer. When I
+talk about @dfn{return value}, I talk about the function value returned by
+the function call. Functions that fail should return @code{nil} as the
+return value.
+
+Some back ends could be said to be @dfn{server-forming} back ends, and
+some might be said not to be. The latter are back ends that generally
+only operate on one group at a time, and have no concept of ``server'';
+they have a group, and they deliver info on that group and nothing
+more.
+
+Gnus identifies each message by way of group name and article number. A
+few remarks about these article numbers might be useful. First of all,
+the numbers are positive integers. Secondly, it is normally not
+possible for later articles to ``re-use'' older article numbers without
+confusing Gnus. That is, if a group has ever contained a message
+numbered 42, then no other message may get that number, or Gnus will get
+mightily confused.@footnote{See the function
+@code{nnchoke-request-update-info}, @ref{Optional Back End Functions}.}
+Third, article numbers must be assigned in order of arrival in the
+group; this is not necessarily the same as the date of the message.
+
+The previous paragraph already mentions all the ``hard'' restrictions that
+article numbers must fulfill. But it seems that it might be useful to
+assign @emph{consecutive} article numbers, for Gnus gets quite confused
+if there are holes in the article numbering sequence. However, due to
+the ``no-reuse'' restriction, holes cannot be avoided altogether. It's
+also useful for the article numbers to start at 1 to avoid running out
+of numbers as long as possible.
+
+Note that by convention, back ends are named @code{nnsomething}, but
+Gnus also comes with some @code{nnnotbackends}, such as
+@file{nnheader.el}, @file{nnmail.el} and @file{nnoo.el}.
+
+In the examples and definitions I will refer to the imaginary back end
+@code{nnchoke}.
+
+@cindex @code{nnchoke}
+
+@menu
+* Required Back End Functions:: Functions that must be implemented.
+* Optional Back End Functions:: Functions that need not be implemented.
+* Error Messaging:: How to get messages and report errors.
+* Writing New Back Ends:: Extending old back ends.
+* Hooking New Back Ends Into Gnus:: What has to be done on the Gnus end.
+* Mail-like Back Ends:: Some tips on mail back ends.
+@end menu
+
+
+@node Required Back End Functions
+@subsubsection Required Back End Functions
+
+@table @code
+
+@item (nnchoke-retrieve-headers ARTICLES &optional GROUP SERVER FETCH-OLD)
+
+@var{articles} is either a range of article numbers or a list of
+@code{Message-ID}s. Current back ends do not fully support either---only
+sequences (lists) of article numbers, and most back ends do not support
+retrieval of @code{Message-ID}s. But they should try for both.
+
+The result data should either be HEADs or @acronym{NOV} lines, and the result
+value should either be @code{headers} or @code{nov} to reflect this.
+This might later be expanded to @code{various}, which will be a mixture
+of HEADs and @acronym{NOV} lines, but this is currently not supported by Gnus.
+
+If @var{fetch-old} is non-@code{nil} it says to try fetching ``extra
+headers'', in some meaning of the word. This is generally done by
+fetching (at most) @var{fetch-old} extra headers less than the smallest
+article number in @code{articles}, and filling the gaps as well. The
+presence of this parameter can be ignored if the back end finds it
+cumbersome to follow the request. If this is non-@code{nil} and not a
+number, do maximum fetches.
+
+Here's an example HEAD:
+
+@example
+221 1056 Article retrieved.
+Path: ifi.uio.no!sturles
+From: sturles@@ifi.uio.no (Sturle Sunde)
+Newsgroups: ifi.discussion
+Subject: Re: Something very droll
+Date: 27 Oct 1994 14:02:57 +0100
+Organization: Dept. of Informatics, University of Oslo, Norway
+Lines: 26
+Message-ID: <38o8e1$a0o@@holmenkollen.ifi.uio.no>
+References: <38jdmq$4qu@@visbur.ifi.uio.no>
+NNTP-Posting-Host: holmenkollen.ifi.uio.no
+.
+@end example
+
+So a @code{headers} return value would imply that there's a number of
+these in the data buffer.
+
+Here's a BNF definition of such a buffer:
+
+@example
+headers = *head
+head = error / valid-head
+error-message = [ "4" / "5" ] 2number " " <error message> eol
+valid-head = valid-message *header "." eol
+valid-message = "221 " <number> " Article retrieved." eol
+header = <text> eol
+@end example
+
+@cindex BNF
+(The version of BNF used here is the one used in RFC822.)
+
+If the return value is @code{nov}, the data buffer should contain
+@dfn{network overview database} lines. These are basically fields
+separated by tabs.
+
+@example
+nov-buffer = *nov-line
+nov-line = field 7*8[ <TAB> field ] eol
+field = <text except TAB>
+@end example
+
+For a closer look at what should be in those fields,
+@pxref{Headers}.
+
+
+@item (nnchoke-open-server SERVER &optional DEFINITIONS)
+
+@var{server} is here the virtual server name. @var{definitions} is a
+list of @code{(VARIABLE VALUE)} pairs that define this virtual server.
+
+If the server can't be opened, no error should be signaled. The back end
+may then choose to refuse further attempts at connecting to this
+server. In fact, it should do so.
+
+If the server is opened already, this function should return a
+non-@code{nil} value. There should be no data returned.
+
+
+@item (nnchoke-close-server &optional SERVER)
+
+Close connection to @var{server} and free all resources connected
+to it. Return @code{nil} if the server couldn't be closed for some
+reason.
+
+There should be no data returned.
+
+
+@item (nnchoke-request-close)
+
+Close connection to all servers and free all resources that the back end
+have reserved. All buffers that have been created by that back end
+should be killed. (Not the @code{nntp-server-buffer}, though.) This
+function is generally only called when Gnus is shutting down.
+
+There should be no data returned.
+
+
+@item (nnchoke-server-opened &optional SERVER)
+
+If @var{server} is the current virtual server, and the connection to the
+physical server is alive, then this function should return a
+non-@code{nil} value. This function should under no circumstances
+attempt to reconnect to a server we have lost connection to.
+
+There should be no data returned.
+
+
+@item (nnchoke-status-message &optional SERVER)
+
+This function should return the last error message from @var{server}.
+
+There should be no data returned.
+
+
+@item (nnchoke-request-article ARTICLE &optional GROUP SERVER TO-BUFFER)
+
+The result data from this function should be the article specified by
+@var{article}. This might either be a @code{Message-ID} or a number.
+It is optional whether to implement retrieval by @code{Message-ID}, but
+it would be nice if that were possible.
+
+If @var{to-buffer} is non-@code{nil}, the result data should be returned
+in this buffer instead of the normal data buffer. This is to make it
+possible to avoid copying large amounts of data from one buffer to
+another, while Gnus mainly requests articles to be inserted directly
+into its article buffer.
+
+If it is at all possible, this function should return a cons cell where
+the @code{car} is the group name the article was fetched from, and the @code{cdr} is
+the article number. This will enable Gnus to find out what the real
+group and article numbers are when fetching articles by
+@code{Message-ID}. If this isn't possible, @code{t} should be returned
+on successful article retrieval.
+
+
+@item (nnchoke-request-group GROUP &optional SERVER FAST INFO)
+
+Get data on @var{group}. This function also has the side effect of
+making @var{group} the current group.
+
+If @var{fast}, don't bother to return useful data, just make @var{group}
+the current group.
+
+If @var{info}, it allows the backend to update the group info
+structure.
+
+Here's an example of some result data and a definition of the same:
+
+@example
+211 56 1000 1059 ifi.discussion
+@end example
+
+The first number is the status, which should be 211. Next is the
+total number of articles in the group, the lowest article number, the
+highest article number, and finally the group name. Note that the total
+number of articles may be less than one might think while just
+considering the highest and lowest article numbers, but some articles
+may have been canceled. Gnus just discards the total-number, so
+whether one should take the bother to generate it properly (if that is a
+problem) is left as an exercise to the reader. If the group contains no
+articles, the lowest article number should be reported as 1 and the
+highest as 0.
+
+@example
+group-status = [ error / info ] eol
+error = [ "4" / "5" ] 2<number> " " <Error message>
+info = "211 " 3* [ <number> " " ] <string>
+@end example
+
+
+@item (nnchoke-close-group GROUP &optional SERVER)
+
+Close @var{group} and free any resources connected to it. This will be
+a no-op on most back ends.
+
+There should be no data returned.
+
+
+@item (nnchoke-request-list &optional SERVER)
+
+Return a list of all groups available on @var{server}. And that means
+@emph{all}.
+
+Here's an example from a server that only carries two groups:
+
+@example
+ifi.test 0000002200 0000002000 y
+ifi.discussion 3324 3300 n
+@end example
+
+On each line we have a group name, then the highest article number in
+that group, the lowest article number, and finally a flag. If the group
+contains no articles, the lowest article number should be reported as 1
+and the highest as 0.
+
+@example
+active-file = *active-line
+active-line = name " " <number> " " <number> " " flags eol
+name = <string>
+flags = "n" / "y" / "m" / "x" / "j" / "=" name
+@end example
+
+The flag says whether the group is read-only (@samp{n}), is moderated
+(@samp{m}), is dead (@samp{x}), is aliased to some other group
+(@samp{=other-group}) or none of the above (@samp{y}).
+
+
+@item (nnchoke-request-post &optional SERVER)
+
+This function should post the current buffer. It might return whether
+the posting was successful or not, but that's not required. If, for
+instance, the posting is done asynchronously, it has generally not been
+completed by the time this function concludes. In that case, this
+function should set up some kind of sentinel to beep the user loud and
+clear if the posting could not be completed.
+
+There should be no result data from this function.
+
+@end table
+
+
+@node Optional Back End Functions
+@subsubsection Optional Back End Functions
+
+@table @code
+
+@item (nnchoke-retrieve-groups GROUPS &optional SERVER)
+
+@var{groups} is a list of groups, and this function should request data
+on all those groups. How it does it is of no concern to Gnus, but it
+should attempt to do this in a speedy fashion.
+
+The return value of this function can be either @code{active} or
+@code{group}, which says what the format of the result data is. The
+former is in the same format as the data from
+@code{nnchoke-request-list}, while the latter is a buffer full of lines
+in the same format as @code{nnchoke-request-group} gives.
+
+@example
+group-buffer = *active-line / *group-status
+@end example
+
+
+@item (nnchoke-request-update-info GROUP INFO &optional SERVER)
+
+A Gnus group info (@pxref{Group Info}) is handed to the back end for
+alterations. This comes in handy if the back end really carries all
+the information (as is the case with virtual and imap groups). This
+function should destructively alter the info to suit its needs, and
+should return a non-@code{nil} value (exceptionally,
+@code{nntp-request-update-info} always returns @code{nil} not to waste
+the network resources).
+
+There should be no result data from this function.
+
+
+@item (nnchoke-request-type GROUP &optional ARTICLE)
+
+When the user issues commands for ``sending news'' (@kbd{F} in the
+summary buffer, for instance), Gnus has to know whether the article the
+user is following up on is news or mail. This function should return
+@code{news} if @var{article} in @var{group} is news, @code{mail} if it
+is mail and @code{unknown} if the type can't be decided. (The
+@var{article} parameter is necessary in @code{nnvirtual} groups which
+might very well combine mail groups and news groups.) Both @var{group}
+and @var{article} may be @code{nil}.
+
+There should be no result data from this function.
+
+
+@item (nnchoke-request-set-mark GROUP ACTION &optional SERVER)
+
+Set/remove/add marks on articles. Normally Gnus handles the article
+marks (such as read, ticked, expired etc.)@: internally, and store them in
+@file{~/.newsrc.eld}. Some back ends (such as @acronym{IMAP}) however carry
+all information about the articles on the server, so Gnus need to
+propagate the mark information to the server.
+
+@var{action} is a list of mark setting requests, having this format:
+
+@example
+(RANGE ACTION MARK)
+@end example
+
+@var{range} is a range of articles you wish to update marks on.
+@var{action} is @code{add} or @code{del}, used to add marks or remove
+marks (preserving all marks not mentioned). @var{mark} is a list of
+marks; where each mark is a symbol. Currently used marks are
+@code{read}, @code{tick}, @code{reply}, @code{expire}, @code{killed},
+@code{dormant}, @code{save}, @code{download}, @code{unsend}, and
+@code{forward}, but your back end should, if possible, not limit
+itself to these.
+
+Given contradictory actions, the last action in the list should be the
+effective one. That is, if your action contains a request to add the
+@code{tick} mark on article 1 and, later in the list, a request to
+remove the mark on the same article, the mark should in fact be removed.
+
+An example action list:
+
+@example
+(((5 12 30) 'del '(tick))
+ ((10 . 90) 'add '(read expire))
+ ((92 94) 'del '(read)))
+@end example
+
+The function should return a range of articles it wasn't able to set the
+mark on (currently not used for anything).
+
+There should be no result data from this function.
+
+@item (nnchoke-request-update-mark GROUP ARTICLE MARK)
+
+If the user tries to set a mark that the back end doesn't like, this
+function may change the mark. Gnus will use whatever this function
+returns as the mark for @var{article} instead of the original
+@var{mark}. If the back end doesn't care, it must return the original
+@var{mark}, and not @code{nil} or any other type of garbage.
+
+The only use for this I can see is what @code{nnvirtual} does with
+it---if a component group is auto-expirable, marking an article as read
+in the virtual group should result in the article being marked as
+expirable.
+
+There should be no result data from this function.
+
+
+@item (nnchoke-request-scan &optional GROUP SERVER)
+
+This function may be called at any time (by Gnus or anything else) to
+request that the back end check for incoming articles, in one way or
+another. A mail back end will typically read the spool file or query
+the @acronym{POP} server when this function is invoked. The
+@var{group} doesn't have to be heeded---if the back end decides that
+it is too much work just scanning for a single group, it may do a
+total scan of all groups. It would be nice, however, to keep things
+local if that's practical.
+
+There should be no result data from this function.
+
+
+@item (nnchoke-request-group-description GROUP &optional SERVER)
+
+The result data from this function should be a description of
+@var{group}.
+
+@example
+description-line = name <TAB> description eol
+name = <string>
+description = <text>
+@end example
+
+@item (nnchoke-request-list-newsgroups &optional SERVER)
+
+The result data from this function should be the description of all
+groups available on the server.
+
+@example
+description-buffer = *description-line
+@end example
+
+
+@item (nnchoke-request-newgroups DATE &optional SERVER)
+
+The result data from this function should be all groups that were
+created after @samp{date}, which is in normal human-readable date format
+(i.e., the date format used in mail and news headers, and returned by
+the function @code{message-make-date} by default). The data should be
+in the active buffer format.
+
+It is okay for this function to return ``too many'' groups; some back ends
+might find it cheaper to return the full list of groups, rather than
+just the new groups. But don't do this for back ends with many groups.
+Normally, if the user creates the groups herself, there won't be too
+many groups, so @code{nnml} and the like are probably safe. But for
+back ends like @code{nntp}, where the groups have been created by the
+server, it is quite likely that there can be many groups.
+
+
+@item (nnchoke-request-create-group GROUP &optional SERVER)
+
+This function should create an empty group with name @var{group}.
+
+There should be no return data.
+
+
+@item (nnchoke-request-expire-articles ARTICLES &optional GROUP SERVER FORCE)
+
+This function should run the expiry process on all articles in the
+@var{articles} range (which is currently a simple list of article
+numbers.) It is left up to the back end to decide how old articles
+should be before they are removed by this function. If @var{force} is
+non-@code{nil}, all @var{articles} should be deleted, no matter how new
+they are.
+
+This function should return a list of articles that it did not/was not
+able to delete.
+
+There should be no result data returned.
+
+
+@item (nnchoke-request-move-article ARTICLE GROUP SERVER ACCEPT-FORM &optional LAST)
+
+This function should move @var{article} (which is a number) from
+@var{group} by calling @var{accept-form}.
+
+This function should ready the article in question for moving by
+removing any header lines it has added to the article, and generally
+should ``tidy up'' the article. Then it should @code{eval}
+@var{accept-form} in the buffer where the ``tidy'' article is. This
+will do the actual copying. If this @code{eval} returns a
+non-@code{nil} value, the article should be removed.
+
+If @var{last} is @code{nil}, that means that there is a high likelihood
+that there will be more requests issued shortly, so that allows some
+optimizations.
+
+The function should return a cons where the @code{car} is the group name and
+the @code{cdr} is the article number that the article was entered as.
+
+There should be no data returned.
+
+
+@item (nnchoke-request-accept-article GROUP &optional SERVER LAST)
+
+This function takes the current buffer and inserts it into @var{group}.
+If @var{last} in @code{nil}, that means that there will be more calls to
+this function in short order.
+
+The function should return a cons where the @code{car} is the group name and
+the @code{cdr} is the article number that the article was entered as.
+
+The group should exist before the back end is asked to accept the
+article for that group.
+
+There should be no data returned.
+
+
+@item (nnchoke-request-replace-article ARTICLE GROUP BUFFER)
+
+This function should remove @var{article} (which is a number) from
+@var{group} and insert @var{buffer} there instead.
+
+There should be no data returned.
+
+
+@item (nnchoke-request-delete-group GROUP FORCE &optional SERVER)
+
+This function should delete @var{group}. If @var{force}, it should
+really delete all the articles in the group, and then delete the group
+itself. (If there is such a thing as ``the group itself''.)
+
+There should be no data returned.
+
+
+@item (nnchoke-request-rename-group GROUP NEW-NAME &optional SERVER)
+
+This function should rename @var{group} into @var{new-name}. All
+articles in @var{group} should move to @var{new-name}.
+
+There should be no data returned.
+
+@end table
+
+
+@node Error Messaging
+@subsubsection Error Messaging
+
+@findex nnheader-report
+@findex nnheader-get-report
+The back ends should use the function @code{nnheader-report} to report
+error conditions---they should not raise errors when they aren't able to
+perform a request. The first argument to this function is the back end
+symbol, and the rest are interpreted as arguments to @code{format} if
+there are multiple of them, or just a string if there is one of them.
+This function must always returns @code{nil}.
+
+@lisp
+(nnheader-report 'nnchoke "You did something totally bogus")
+
+(nnheader-report 'nnchoke "Could not request group %s" group)
+@end lisp
+
+Gnus, in turn, will call @code{nnheader-get-report} when it gets a
+@code{nil} back from a server, and this function returns the most
+recently reported message for the back end in question. This function
+takes one argument---the server symbol.
+
+Internally, these functions access @var{back-end}@code{-status-string},
+so the @code{nnchoke} back end will have its error message stored in
+@code{nnchoke-status-string}.
+
+
+@node Writing New Back Ends
+@subsubsection Writing New Back Ends
+
+Many back ends are quite similar. @code{nnml} is just like
+@code{nnspool}, but it allows you to edit the articles on the server.
+@code{nnmh} is just like @code{nnml}, but it doesn't use an active file,
+and it doesn't maintain overview databases. @code{nndir} is just like
+@code{nnml}, but it has no concept of ``groups'', and it doesn't allow
+editing articles.
+
+It would make sense if it were possible to ``inherit'' functions from
+back ends when writing new back ends. And, indeed, you can do that if you
+want to. (You don't have to if you don't want to, of course.)
+
+All the back ends declare their public variables and functions by using a
+package called @code{nnoo}.
+
+To inherit functions from other back ends (and allow other back ends to
+inherit functions from the current back end), you should use the
+following macros:
+
+@table @code
+
+@item nnoo-declare
+This macro declares the first parameter to be a child of the subsequent
+parameters. For instance:
+
+@lisp
+(nnoo-declare nndir
+ nnml nnmh)
+@end lisp
+
+@code{nndir} has declared here that it intends to inherit functions from
+both @code{nnml} and @code{nnmh}.
+
+@item defvoo
+This macro is equivalent to @code{defvar}, but registers the variable as
+a public server variable. Most state-oriented variables should be
+declared with @code{defvoo} instead of @code{defvar}.
+
+In addition to the normal @code{defvar} parameters, it takes a list of
+variables in the parent back ends to map the variable to when executing
+a function in those back ends.
+
+@lisp
+(defvoo nndir-directory nil
+ "Where nndir will look for groups."
+ nnml-current-directory nnmh-current-directory)
+@end lisp
+
+This means that @code{nnml-current-directory} will be set to
+@code{nndir-directory} when an @code{nnml} function is called on behalf
+of @code{nndir}. (The same with @code{nnmh}.)
+
+@item nnoo-define-basics
+This macro defines some common functions that almost all back ends should
+have.
+
+@lisp
+(nnoo-define-basics nndir)
+@end lisp
+
+@item deffoo
+This macro is just like @code{defun} and takes the same parameters. In
+addition to doing the normal @code{defun} things, it registers the
+function as being public so that other back ends can inherit it.
+
+@item nnoo-map-functions
+This macro allows mapping of functions from the current back end to
+functions from the parent back ends.
+
+@lisp
+(nnoo-map-functions nndir
+ (nnml-retrieve-headers 0 nndir-current-group 0 0)
+ (nnmh-request-article 0 nndir-current-group 0 0))
+@end lisp
+
+This means that when @code{nndir-retrieve-headers} is called, the first,
+third, and fourth parameters will be passed on to
+@code{nnml-retrieve-headers}, while the second parameter is set to the
+value of @code{nndir-current-group}.
+
+@item nnoo-import
+This macro allows importing functions from back ends. It should be the
+last thing in the source file, since it will only define functions that
+haven't already been defined.
+
+@lisp
+(nnoo-import nndir
+ (nnmh
+ nnmh-request-list
+ nnmh-request-newgroups)
+ (nnml))
+@end lisp
+
+This means that calls to @code{nndir-request-list} should just be passed
+on to @code{nnmh-request-list}, while all public functions from
+@code{nnml} that haven't been defined in @code{nndir} yet should be
+defined now.
+
+@end table
+
+Below is a slightly shortened version of the @code{nndir} back end.
+
+@lisp
+;;; @r{nndir.el --- single directory newsgroup access for Gnus}
+;; @r{Copyright (C) 1995,1996 Free Software Foundation, Inc.}
+
+;;; @r{Code:}
+
+(require 'nnheader)
+(require 'nnmh)
+(require 'nnml)
+(require 'nnoo)
+(eval-when-compile (require 'cl))
+
+(nnoo-declare nndir
+ nnml nnmh)
+
+(defvoo nndir-directory nil
+ "Where nndir will look for groups."
+ nnml-current-directory nnmh-current-directory)
+
+(defvoo nndir-nov-is-evil nil
+ "*Non-nil means that nndir will never retrieve NOV headers."
+ nnml-nov-is-evil)
+
+(defvoo nndir-current-group ""
+ nil
+ nnml-current-group nnmh-current-group)
+(defvoo nndir-top-directory nil nil nnml-directory nnmh-directory)
+(defvoo nndir-get-new-mail nil nil nnml-get-new-mail nnmh-get-new-mail)
+
+(defvoo nndir-status-string "" nil nnmh-status-string)
+(defconst nndir-version "nndir 1.0")
+
+;;; @r{Interface functions.}
+
+(nnoo-define-basics nndir)
+
+(deffoo nndir-open-server (server &optional defs)
+ (setq nndir-directory
+ (or (cadr (assq 'nndir-directory defs))
+ server))
+ (unless (assq 'nndir-directory defs)
+ (push `(nndir-directory ,server) defs))
+ (push `(nndir-current-group
+ ,(file-name-nondirectory
+ (directory-file-name nndir-directory)))
+ defs)
+ (push `(nndir-top-directory
+ ,(file-name-directory (directory-file-name nndir-directory)))
+ defs)
+ (nnoo-change-server 'nndir server defs))
+
+(nnoo-map-functions nndir
+ (nnml-retrieve-headers 0 nndir-current-group 0 0)
+ (nnmh-request-article 0 nndir-current-group 0 0)
+ (nnmh-request-group nndir-current-group 0 0)
+ (nnmh-close-group nndir-current-group 0))
+
+(nnoo-import nndir
+ (nnmh
+ nnmh-status-message
+ nnmh-request-list
+ nnmh-request-newgroups))
+
+(provide 'nndir)
+@end lisp
+
+
+@node Hooking New Back Ends Into Gnus
+@subsubsection Hooking New Back Ends Into Gnus
+
+@vindex gnus-valid-select-methods
+@findex gnus-declare-backend
+Having Gnus start using your new back end is rather easy---you just
+declare it with the @code{gnus-declare-backend} functions. This will
+enter the back end into the @code{gnus-valid-select-methods} variable.
+
+@code{gnus-declare-backend} takes two parameters---the back end name and
+an arbitrary number of @dfn{abilities}.
+
+Here's an example:
+
+@lisp
+(gnus-declare-backend "nnchoke" 'mail 'respool 'address)
+@end lisp
+
+The above line would then go in the @file{nnchoke.el} file.
+
+The abilities can be:
+
+@table @code
+@item mail
+This is a mailish back end---followups should (probably) go via mail.
+@item post
+This is a newsish back end---followups should (probably) go via news.
+@item post-mail
+This back end supports both mail and news.
+@item none
+This is neither a post nor mail back end---it's something completely
+different.
+@item respool
+It supports respooling---or rather, it is able to modify its source
+articles and groups.
+@item address
+The name of the server should be in the virtual server name. This is
+true for almost all back ends.
+@item prompt-address
+The user should be prompted for an address when doing commands like
+@kbd{B} in the group buffer. This is true for back ends like
+@code{nntp}, but not @code{nnmbox}, for instance.
+@end table
+
+
+@node Mail-like Back Ends
+@subsubsection Mail-like Back Ends
+
+One of the things that separate the mail back ends from the rest of the
+back ends is the heavy dependence by most of the mail back ends on
+common functions in @file{nnmail.el}. For instance, here's the
+definition of @code{nnml-request-scan}:
+
+@lisp
+(deffoo nnml-request-scan (&optional group server)
+ (setq nnml-article-file-alist nil)
+ (nnmail-get-new-mail 'nnml 'nnml-save-nov nnml-directory group))
+@end lisp
+
+It simply calls @code{nnmail-get-new-mail} with a few parameters,
+and @code{nnmail} takes care of all the moving and splitting of the
+mail.
+
+This function takes four parameters.
+
+@table @var
+@item method
+This should be a symbol to designate which back end is responsible for
+the call.
+
+@item exit-function
+This function should be called after the splitting has been performed.
+
+@item temp-directory
+Where the temporary files should be stored.
+
+@item group
+This optional argument should be a group name if the splitting is to be
+performed for one group only.
+@end table
+
+@code{nnmail-get-new-mail} will call @var{back-end}@code{-save-mail} to
+save each article. @var{back-end}@code{-active-number} will be called to
+find the article number assigned to this article.
+
+The function also uses the following variables:
+@var{back-end}@code{-get-new-mail} (to see whether to get new mail for
+this back end); and @var{back-end}@code{-group-alist} and
+@var{back-end}@code{-active-file} to generate the new active file.
+@var{back-end}@code{-group-alist} should be a group-active alist, like
+this:
+
+@example
+(("a-group" (1 . 10))
+ ("some-group" (34 . 39)))
+@end example
+
+
+@node Score File Syntax
+@subsection Score File Syntax
+
+Score files are meant to be easily parsable, but yet extremely
+malleable. It was decided that something that had the same read syntax
+as an Emacs Lisp list would fit that spec.
+
+Here's a typical score file:
+
+@lisp
+(("summary"
+ ("Windows 95" -10000 nil s)
+ ("Gnus"))
+ ("from"
+ ("Lars" -1000))
+ (mark -100))
+@end lisp
+
+BNF definition of a score file:
+
+@example
+score-file = "" / "(" *element ")"
+element = rule / atom
+rule = string-rule / number-rule / date-rule
+string-rule = "(" quote string-header quote space *string-match ")"
+number-rule = "(" quote number-header quote space *number-match ")"
+date-rule = "(" quote date-header quote space *date-match ")"
+quote = <ascii 34>
+string-header = "subject" / "from" / "references" / "message-id" /
+ "xref" / "body" / "head" / "all" / "followup"
+number-header = "lines" / "chars"
+date-header = "date"
+string-match = "(" quote <string> quote [ "" / [ space score [ "" /
+ space date [ "" / [ space string-match-t ] ] ] ] ] ")"
+score = "nil" / <integer>
+date = "nil" / <natural number>
+string-match-t = "nil" / "s" / "substring" / "S" / "Substring" /
+ "r" / "regex" / "R" / "Regex" /
+ "e" / "exact" / "E" / "Exact" /
+ "f" / "fuzzy" / "F" / "Fuzzy"
+number-match = "(" <integer> [ "" / [ space score [ "" /
+ space date [ "" / [ space number-match-t ] ] ] ] ] ")"
+number-match-t = "nil" / "=" / "<" / ">" / ">=" / "<="
+date-match = "(" quote <string> quote [ "" / [ space score [ "" /
+ space date [ "" / [ space date-match-t ] ] ] ] ")"
+date-match-t = "nil" / "at" / "before" / "after"
+atom = "(" [ required-atom / optional-atom ] ")"
+required-atom = mark / expunge / mark-and-expunge / files /
+ exclude-files / read-only / touched
+optional-atom = adapt / local / eval
+mark = "mark" space nil-or-number
+nil-or-number = "nil" / <integer>
+expunge = "expunge" space nil-or-number
+mark-and-expunge = "mark-and-expunge" space nil-or-number
+files = "files" *[ space <string> ]
+exclude-files = "exclude-files" *[ space <string> ]
+read-only = "read-only" [ space "nil" / space "t" ]
+adapt = "adapt" [ space "ignore" / space "t" / space adapt-rule ]
+adapt-rule = "(" *[ <string> *[ "(" <string> <integer> ")" ] ")"
+local = "local" *[ space "(" <string> space <form> ")" ]
+eval = "eval" space <form>
+space = *[ " " / <TAB> / <NEWLINE> ]
+@end example
+
+Any unrecognized elements in a score file should be ignored, but not
+discarded.
+
+As you can see, white space is needed, but the type and amount of white
+space is irrelevant. This means that formatting of the score file is
+left up to the programmer---if it's simpler to just spew it all out on
+one looong line, then that's ok.
+
+The meaning of the various atoms are explained elsewhere in this
+manual (@pxref{Score File Format}).
+
+
+@node Headers
+@subsection Headers
+
+Internally Gnus uses a format for storing article headers that
+corresponds to the @acronym{NOV} format in a mysterious fashion. One could
+almost suspect that the author looked at the @acronym{NOV} specification and
+just shamelessly @emph{stole} the entire thing, and one would be right.
+
+@dfn{Header} is a severely overloaded term. ``Header'' is used in
+RFC 1036 to talk about lines in the head of an article (e.g.,
+@code{From}). It is used by many people as a synonym for
+``head''---``the header and the body''. (That should be avoided, in my
+opinion.) And Gnus uses a format internally that it calls ``header'',
+which is what I'm talking about here. This is a 9-element vector,
+basically, with each header (ouch) having one slot.
+
+These slots are, in order: @code{number}, @code{subject}, @code{from},
+@code{date}, @code{id}, @code{references}, @code{chars}, @code{lines},
+@code{xref}, and @code{extra}. There are macros for accessing and
+setting these slots---they all have predictable names beginning with
+@code{mail-header-} and @code{mail-header-set-}, respectively.
+
+All these slots contain strings, except the @code{extra} slot, which
+contains an alist of header/value pairs (@pxref{To From Newsgroups}).
+
+
+@node Ranges
+@subsection Ranges
+
+@sc{gnus} introduced a concept that I found so useful that I've started
+using it a lot and have elaborated on it greatly.
+
+The question is simple: If you have a large amount of objects that are
+identified by numbers (say, articles, to take a @emph{wild} example)
+that you want to qualify as being ``included'', a normal sequence isn't
+very useful. (A 200,000 length sequence is a bit long-winded.)
+
+The solution is as simple as the question: You just collapse the
+sequence.
+
+@example
+(1 2 3 4 5 6 10 11 12)
+@end example
+
+is transformed into
+
+@example
+((1 . 6) (10 . 12))
+@end example
+
+To avoid having those nasty @samp{(13 . 13)} elements to denote a
+lonesome object, a @samp{13} is a valid element:
+
+@example
+((1 . 6) 7 (10 . 12))
+@end example
+
+This means that comparing two ranges to find out whether they are equal
+is slightly tricky:
+
+@example
+((1 . 5) 7 8 (10 . 12))
+@end example
+
+and
+
+@example
+((1 . 5) (7 . 8) (10 . 12))
+@end example
+
+are equal. In fact, any non-descending list is a range:
+
+@example
+(1 2 3 4 5)
+@end example
+
+is a perfectly valid range, although a pretty long-winded one. This is
+also valid:
+
+@example
+(1 . 5)
+@end example
+
+and is equal to the previous range.
+
+Here's a BNF definition of ranges. Of course, one must remember the
+semantic requirement that the numbers are non-descending. (Any number
+of repetition of the same number is allowed, but apt to disappear in
+range handling.)
+
+@example
+range = simple-range / normal-range
+simple-range = "(" number " . " number ")"
+normal-range = "(" start-contents ")"
+contents = "" / simple-range *[ " " contents ] /
+ number *[ " " contents ]
+@end example
+
+Gnus currently uses ranges to keep track of read articles and article
+marks. I plan on implementing a number of range operators in C if The
+Powers That Be are willing to let me. (I haven't asked yet, because I
+need to do some more thinking on what operators I need to make life
+totally range-based without ever having to convert back to normal
+sequences.)
+
+
+@node Group Info
+@subsection Group Info
+
+Gnus stores all permanent info on groups in a @dfn{group info} list.
+This list is from three to six elements (or more) long and exhaustively
+describes the group.
+
+Here are two example group infos; one is a very simple group while the
+second is a more complex one:
+
+@example
+("no.group" 5 ((1 . 54324)))
+
+("nnml:my.mail" 3 ((1 . 5) 9 (20 . 55))
+ ((tick (15 . 19)) (replied 3 6 (19 . 3)))
+ (nnml "")
+ ((auto-expire . t) (to-address . "ding@@gnus.org")))
+@end example
+
+The first element is the @dfn{group name}---as Gnus knows the group,
+anyway. The second element is the @dfn{subscription level}, which
+normally is a small integer. (It can also be the @dfn{rank}, which is a
+cons cell where the @code{car} is the level and the @code{cdr} is the
+score.) The third element is a list of ranges of read articles. The
+fourth element is a list of lists of article marks of various kinds.
+The fifth element is the select method (or virtual server, if you like).
+The sixth element is a list of @dfn{group parameters}, which is what
+this section is about.
+
+Any of the last three elements may be missing if they are not required.
+In fact, the vast majority of groups will normally only have the first
+three elements, which saves quite a lot of cons cells.
+
+Here's a BNF definition of the group info format:
+
+@example
+info = "(" group space ralevel space read
+ [ "" / [ space marks-list [ "" / [ space method [ "" /
+ space parameters ] ] ] ] ] ")"
+group = quote <string> quote
+ralevel = rank / level
+level = <integer in the range of 1 to inf>
+rank = "(" level "." score ")"
+score = <integer in the range of 1 to inf>
+read = range
+marks-lists = nil / "(" *marks ")"
+marks = "(" <string> range ")"
+method = "(" <string> *elisp-forms ")"
+parameters = "(" *elisp-forms ")"
+@end example
+
+Actually that @samp{marks} rule is a fib. A @samp{marks} is a
+@samp{<string>} consed on to a @samp{range}, but that's a bitch to say
+in pseudo-BNF.
+
+If you have a Gnus info and want to access the elements, Gnus offers a
+series of macros for getting/setting these elements.
+
+@table @code
+@item gnus-info-group
+@itemx gnus-info-set-group
+@findex gnus-info-group
+@findex gnus-info-set-group
+Get/set the group name.
+
+@item gnus-info-rank
+@itemx gnus-info-set-rank
+@findex gnus-info-rank
+@findex gnus-info-set-rank
+Get/set the group rank (@pxref{Group Score}).
+
+@item gnus-info-level
+@itemx gnus-info-set-level
+@findex gnus-info-level
+@findex gnus-info-set-level
+Get/set the group level.
+
+@item gnus-info-score
+@itemx gnus-info-set-score
+@findex gnus-info-score
+@findex gnus-info-set-score
+Get/set the group score (@pxref{Group Score}).
+
+@item gnus-info-read
+@itemx gnus-info-set-read
+@findex gnus-info-read
+@findex gnus-info-set-read
+Get/set the ranges of read articles.
+
+@item gnus-info-marks
+@itemx gnus-info-set-marks
+@findex gnus-info-marks
+@findex gnus-info-set-marks
+Get/set the lists of ranges of marked articles.
+
+@item gnus-info-method
+@itemx gnus-info-set-method
+@findex gnus-info-method
+@findex gnus-info-set-method
+Get/set the group select method.
+
+@item gnus-info-params
+@itemx gnus-info-set-params
+@findex gnus-info-params
+@findex gnus-info-set-params
+Get/set the group parameters.
+@end table
+
+All the getter functions take one parameter---the info list. The setter
+functions take two parameters---the info list and the new value.
+
+The last three elements in the group info aren't mandatory, so it may be
+necessary to extend the group info before setting the element. If this
+is necessary, you can just pass on a non-@code{nil} third parameter to
+the three final setter functions to have this happen automatically.
+
+
+@node Extended Interactive
+@subsection Extended Interactive
+@cindex interactive
+@findex gnus-interactive
+
+Gnus extends the standard Emacs @code{interactive} specification
+slightly to allow easy use of the symbolic prefix (@pxref{Symbolic
+Prefixes}). Here's an example of how this is used:
+
+@lisp
+(defun gnus-summary-increase-score (&optional score symp)
+ (interactive (gnus-interactive "P\ny"))
+ ...
+ )
+@end lisp
+
+The best thing to do would have been to implement
+@code{gnus-interactive} as a macro which would have returned an
+@code{interactive} form, but this isn't possible since Emacs checks
+whether a function is interactive or not by simply doing an @code{assq}
+on the lambda form. So, instead we have @code{gnus-interactive}
+function that takes a string and returns values that are usable to
+@code{interactive}.
+
+This function accepts (almost) all normal @code{interactive} specs, but
+adds a few more.
+
+@table @samp
+@item y
+@vindex gnus-current-prefix-symbol
+The current symbolic prefix---the @code{gnus-current-prefix-symbol}
+variable.
+
+@item Y
+@vindex gnus-current-prefix-symbols
+A list of the current symbolic prefixes---the
+@code{gnus-current-prefix-symbol} variable.
+
+@item A
+The current article number---the @code{gnus-summary-article-number}
+function.
+
+@item H
+The current article header---the @code{gnus-summary-article-header}
+function.
+
+@item g
+The current group name---the @code{gnus-group-group-name}
+function.
+
+@end table
+
+
+@node Emacs/XEmacs Code
+@subsection Emacs/XEmacs Code
+@cindex XEmacs
+@cindex Emacsen
+
+While Gnus runs under Emacs, XEmacs and Mule, I decided that one of the
+platforms must be the primary one. I chose Emacs. Not because I don't
+like XEmacs or Mule, but because it comes first alphabetically.
+
+This means that Gnus will byte-compile under Emacs with nary a warning,
+while XEmacs will pump out gigabytes of warnings while byte-compiling.
+As I use byte-compilation warnings to help me root out trivial errors in
+Gnus, that's very useful.
+
+I've also consistently used Emacs function interfaces, but have used
+Gnusey aliases for the functions. To take an example: Emacs defines a
+@code{run-at-time} function while XEmacs defines a @code{start-itimer}
+function. I then define a function called @code{gnus-run-at-time} that
+takes the same parameters as the Emacs @code{run-at-time}. When running
+Gnus under Emacs, the former function is just an alias for the latter.
+However, when running under XEmacs, the former is an alias for the
+following function:
+
+@lisp
+(defun gnus-xmas-run-at-time (time repeat function &rest args)
+ (start-itimer
+ "gnus-run-at-time"
+ `(lambda ()
+ (,function ,@@args))
+ time repeat))
+@end lisp
+
+This sort of thing has been done for bunches of functions. Gnus does
+not redefine any native Emacs functions while running under XEmacs---it
+does this @code{defalias} thing with Gnus equivalents instead. Cleaner
+all over.
+
+In the cases where the XEmacs function interface was obviously cleaner,
+I used it instead. For example @code{gnus-region-active-p} is an alias
+for @code{region-active-p} in XEmacs, whereas in Emacs it is a function.
+
+Of course, I could have chosen XEmacs as my native platform and done
+mapping functions the other way around. But I didn't. The performance
+hit these indirections impose on Gnus under XEmacs should be slight.
+
+
+@node Various File Formats
+@subsection Various File Formats
+
+@menu
+* Active File Format:: Information on articles and groups available.
+* Newsgroups File Format:: Group descriptions.
+@end menu
+
+
+@node Active File Format
+@subsubsection Active File Format
+
+The active file lists all groups available on the server in
+question. It also lists the highest and lowest current article numbers
+in each group.
+
+Here's an excerpt from a typical active file:
+
+@example
+soc.motss 296030 293865 y
+alt.binaries.pictures.fractals 3922 3913 n
+comp.sources.unix 1605 1593 m
+comp.binaries.ibm.pc 5097 5089 y
+no.general 1000 900 y
+@end example
+
+Here's a pseudo-BNF definition of this file:
+
+@example
+active = *group-line
+group-line = group spc high-number spc low-number spc flag <NEWLINE>
+group = <non-white-space string>
+spc = " "
+high-number = <non-negative integer>
+low-number = <positive integer>
+flag = "y" / "n" / "m" / "j" / "x" / "=" group
+@end example
+
+For a full description of this file, see the manual pages for
+@samp{innd}, in particular @samp{active(5)}.
+
+
+@node Newsgroups File Format
+@subsubsection Newsgroups File Format
+
+The newsgroups file lists groups along with their descriptions. Not all
+groups on the server have to be listed, and not all groups in the file
+have to exist on the server. The file is meant purely as information to
+the user.
+
+The format is quite simple; a group name, a tab, and the description.
+Here's the definition:
+
+@example
+newsgroups = *line
+line = group tab description <NEWLINE>
+group = <non-white-space string>
+tab = <TAB>
+description = <string>
+@end example
+
+
+@page
+@node Emacs for Heathens
+@section Emacs for Heathens
+
+Believe it or not, but some people who use Gnus haven't really used
+Emacs much before they embarked on their journey on the Gnus Love Boat.
+If you are one of those unfortunates whom ``@kbd{C-M-a}'', ``kill the
+region'', and ``set @code{gnus-flargblossen} to an alist where the key
+is a regexp that is used for matching on the group name'' are magical
+phrases with little or no meaning, then this appendix is for you. If
+you are already familiar with Emacs, just ignore this and go fondle your
+cat instead.
+
+@menu
+* Keystrokes:: Entering text and executing commands.
+* Emacs Lisp:: The built-in Emacs programming language.
+@end menu
+
+
+@node Keystrokes
+@subsection Keystrokes
+
+@itemize @bullet
+@item
+Q: What is an experienced Emacs user?
+
+@item
+A: A person who wishes that the terminal had pedals.
+@end itemize
+
+Yes, when you use Emacs, you are apt to use the control key, the shift
+key and the meta key a lot. This is very annoying to some people
+(notably @code{vi}le users), and the rest of us just love the hell out
+of it. Just give up and submit. Emacs really does stand for
+``Escape-Meta-Alt-Control-Shift'', and not ``Editing Macros'', as you
+may have heard from other disreputable sources (like the Emacs author).
+
+The shift keys are normally located near your pinky fingers, and are
+normally used to get capital letters and stuff. You probably use it all
+the time. The control key is normally marked ``CTRL'' or something like
+that. The meta key is, funnily enough, never marked as such on any
+keyboard. The one I'm currently at has a key that's marked ``Alt'',
+which is the meta key on this keyboard. It's usually located somewhere
+to the left hand side of the keyboard, usually on the bottom row.
+
+Now, us Emacs people don't say ``press the meta-control-m key'',
+because that's just too inconvenient. We say ``press the @kbd{C-M-m}
+key''. @kbd{M-} is the prefix that means ``meta'' and ``C-'' is the
+prefix that means ``control''. So ``press @kbd{C-k}'' means ``press
+down the control key, and hold it down while you press @kbd{k}''.
+``Press @kbd{C-M-k}'' means ``press down and hold down the meta key and
+the control key and then press @kbd{k}''. Simple, ay?
+
+This is somewhat complicated by the fact that not all keyboards have a
+meta key. In that case you can use the ``escape'' key. Then @kbd{M-k}
+means ``press escape, release escape, press @kbd{k}''. That's much more
+work than if you have a meta key, so if that's the case, I respectfully
+suggest you get a real keyboard with a meta key. You can't live without
+it.
+
+
+
+@node Emacs Lisp
+@subsection Emacs Lisp
+
+Emacs is the King of Editors because it's really a Lisp interpreter.
+Each and every key you tap runs some Emacs Lisp code snippet, and since
+Emacs Lisp is an interpreted language, that means that you can configure
+any key to run any arbitrary code. You just, like, do it.
+
+Gnus is written in Emacs Lisp, and is run as a bunch of interpreted
+functions. (These are byte-compiled for speed, but it's still
+interpreted.) If you decide that you don't like the way Gnus does
+certain things, it's trivial to have it do something a different way.
+(Well, at least if you know how to write Lisp code.) However, that's
+beyond the scope of this manual, so we are simply going to talk about
+some common constructs that you normally use in your @file{~/.gnus.el}
+file to customize Gnus. (You can also use the @file{~/.emacs} file, but
+in order to set things of Gnus up, it is much better to use the
+@file{~/.gnus.el} file, @xref{Startup Files}.)
+
+If you want to set the variable @code{gnus-florgbnize} to four (4), you
+write the following:
+
+@lisp
+(setq gnus-florgbnize 4)
+@end lisp
+
+This function (really ``special form'') @code{setq} is the one that can
+set a variable to some value. This is really all you need to know. Now
+you can go and fill your @file{~/.gnus.el} file with lots of these to
+change how Gnus works.
+
+If you have put that thing in your @file{~/.gnus.el} file, it will be
+read and @code{eval}ed (which is Lisp-ese for ``run'') the next time you
+start Gnus. If you want to change the variable right away, simply say
+@kbd{C-x C-e} after the closing parenthesis. That will @code{eval} the
+previous ``form'', which is a simple @code{setq} statement here.
+
+Go ahead---just try it, if you're located at your Emacs. After you
+@kbd{C-x C-e}, you will see @samp{4} appear in the echo area, which
+is the return value of the form you @code{eval}ed.
+
+Some pitfalls:
+
+If the manual says ``set @code{gnus-read-active-file} to @code{some}'',
+that means:
+
+@lisp
+(setq gnus-read-active-file 'some)
+@end lisp
+
+On the other hand, if the manual says ``set @code{gnus-nntp-server-file} to
+@samp{/etc/nntpserver}'', that means:
+
+@lisp
+(setq gnus-nntp-server-file "/etc/nntpserver")
+@end lisp
+
+So be careful not to mix up strings (the latter) with symbols (the
+former). The manual is unambiguous, but it can be confusing.
+
+@page
+@include gnus-faq.texi
+
+@node GNU Free Documentation License
+@chapter GNU Free Documentation License
+@include doclicense.texi
+
+@node Index
+@chapter Index
+@printindex cp
+
+@node Key Index
+@chapter Key Index
+@printindex ky
+
+@bye
+
+@iftex
+@iflatex
+\end{document}
+@end iflatex
+@end iftex
+
+@c Local Variables:
+@c mode: texinfo
+@c coding: utf-8
+@c End:
projects / packages / blobdiff