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[gnus] / texi / gnus.texi

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\gnusauthor{by Lars Magne Ingebrigtsen}
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Copyright \copyright{} 1995,96 Free Software Foundation, Inc. 

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.

\newpage
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@ifinfo

This file documents Gnus, the GNU Emacs newsreader.

Copyright (C) 1995,96 Free Software Foundation, Inc.

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

@ignore
Permission is granted to process this file through Tex and print the
results, provided the printed document carries copying permission
notice identical to this one except for the removal of this paragraph
(this paragraph not being relevant to the printed manual).

@end ignore
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.
@end ifinfo

@tex

@titlepage
@title Gnus 5.4.54 Manual

@author by Lars Magne Ingebrigtsen
@page

@vskip 0pt plus 1filll
Copyright @copyright{} 1995,96,97 Free Software Foundation, Inc. 

Permission is granted to make and distribute verbatim copies of
this manual provided the copyright notice and this permission notice
are preserved on all copies.

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual
into another language, under the above conditions for modified versions.

@end titlepage
@page

@end tex


@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---@sc{nntp}, local
spool or your mbox file.  All at the same time, if you want to push your
luck.

This manual corresponds to Gnus 5.4.54.

@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.

@end iftex


@menu
* Starting Up::           Finding news can be a pain.
* The Group Buffer::      Selecting, subscribing and killing groups.
* The Summary Buffer::    Reading, saving and posting articles.
* The 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.
* Various::               General purpose settings.
* The End::               Farewell and goodbye.
* Appendices::            Terminology, Emacs intro, FAQ, History, Internals.
* Index::                 Variable, function and concept index.
* Key Index::             Key Index.
@end menu

@node Starting Up
@chapter Starting Gnus
@cindex starting up

@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. 

@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. 

@menu
* Finding the News::    Choosing a method for getting news.
* The First Time::      What does Gnus do the first time you start it?
* 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?
* 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.
* Changing Servers::    You may want to move from one server to another.
* Startup Variables::   Other variables you might change.
@end menu


@node Finding the News
@section Finding the News
@cindex finding news

@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 that are not fetched with this method are
foreign groups.

For instance, if the @samp{news.somewhere.edu} @sc{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.

@vindex gnus-nntpserver-file
@cindex NNTPSERVER
@cindex @sc{nntp} server
If this variable is not set, Gnus will take a look at the
@code{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 will try to use the machine that is
running Emacs as an @sc{nntp} server.  That's a long shot, though.

@vindex gnus-nntp-server
If @code{gnus-nntp-server} is set, this variable will override
@code{gnus-select-method}.  You should therefore set
@code{gnus-nntp-server} to @code{nil}, which is what it is by default.

@vindex gnus-secondary-servers
You can also make Gnus prompt you interactively for the name of an
@sc{nntp} server.  If you give a non-numerical prefix to @code{gnus}
(i.e., @kbd{C-u M-x gnus}), Gnus will let you choose between the servers
in the @code{gnus-secondary-servers} list (if any).  You can also just
type in the name of any server you feel like visiting.

@findex gnus-group-browse-foreign-server
@kindex B (Group)
However, if you use one @sc{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} backend to read your mail, you
would typically set this variable to

@lisp
(setq gnus-secondary-select-methods '((nnmbox "")))
@end lisp


@node The First Time
@section The First Time
@cindex first time usage

If no startup files exist, Gnus will try to determine what groups should
be subscribed by default.

@vindex gnus-default-subscribed-newsgroups
If the variable @code{gnus-default-subscribed-newsgroups} is set, Gnus
will subscribe you to just those groups in that list, leaving the rest
killed.  Your system administrator should have set this variable to
something useful.

Since she hasn't, Gnus will just subscribe you to a few arbitrarily
picked groups (i.e., @samp{*.newusers}).  (@dfn{Arbitrary} is here
defined as @dfn{whatever Lars thinks you should read}.)

You'll also be subscribed to the Gnus documentation group, which should
help you with most common problems.  

If @code{gnus-default-subscribed-newsgroups} is @code{t}, Gnus will just
use the normal functions for handling new groups, and not do anything
special.


@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.)


@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
@code{.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.)

Anyways, 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) @code{.newsrc} file.


@node Fetching a Group
@section Fetching a Group
@cindex fetching a group

@findex gnus-fetch-group
It it 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 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{t} by default.  If you set this variable to @code{always}, then
Gnus will query the backends 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 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.  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 randomly.

@item gnus-subscribe-alphabetically
@vindex gnus-subscribe-alphabetically
Subscribe all new groups alphabetically.

@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 it's
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.

@item gnus-subscribe-killed
@vindex gnus-subscribe-killed
Kill all new groups.

@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 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}.

@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 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 backends (@code{nnml}, @code{nnbabyl},
@code{nnfolder}, @code{nnmbox}, and @code{nnmh}) subscribed.  If you
don't like that, just set this variable to @code{nil}.

New groups that match this regexp 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 @sc{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
@sc{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.  

Gnus provides a few functions to attempt to translate a @file{.newsrc}
file from one server to another.  They all have one thing in
common---they take a looong time to run.  You don't want to use these
functions more than absolutely necessary.

@kindex M-x gnus-change-server
@findex gnus-change-server
If you have access to both servers, Gnus can request the headers for all
the articles you have read and compare @code{Message-ID}s and map the
article numbers of the read articles and article marks.  The @kbd{M-x
gnus-change-server} command will do this for all your native groups.  It
will prompt for the method you want to move to.

@kindex M-x gnus-group-move-group-to-server
@findex gnus-group-move-group-to-server
You can also move individual groups with the @kbd{M-x
gnus-group-move-group-to-server} command.  This is useful if you want to
move a (foreign) group from one server to another.

@kindex M-x gnus-group-clear-data-on-native-groups
@findex gnus-group-clear-data-on-native-groups
If you don't have access to both the old and new server, all your marks
and read ranges have become worthless.  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.


@node Startup Files
@section Startup Files
@cindex startup files
@cindex .newsrc
@cindex .newsrc.el
@cindex .newsrc.eld

Now, you all know about the @file{.newsrc} file.  All subscription
information is traditionally stored in this file.

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.

@vindex gnus-save-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 making exit from Gnus faster.
However, this will make it impossible to use other newsreaders than
Gnus.  But hey, who would want to, right?

@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
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.

@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
When Gnus starts, it will read the @code{gnus-site-init-file}
(@file{.../site-lisp/gnus} 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).



@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 @code{.newsrc} file.


@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{t} 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.

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
@sc{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.

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 that is 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-startup-hook
@vindex gnus-startup-hook
A hook that is run after starting up Gnus successfully.

@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-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 @code{.emacs} instead.

@item gnus-no-groups-message
@vindex gnus-no-groups-message
Message displayed by Gnus when no groups are available.

@item gnus-play-startup-jingle
@vindex gnus-play-startup-jingle
If non-@code{nil}, play the Gnus jingle at startup.

@item gnus-startup-jingle
@vindex gnus-startup-jingle
Jingle to be played if the above variable is non-@code{nil}.  The
default is @samp{Tuxedomoon.Jingle4.au}.

@end table


@node The Group Buffer
@chapter The Group Buffer
@cindex group buffer

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.

@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.
* Group Data::             Changing the info for a group.
* Subscription Commands::  Unsubscribing, killing, subscribing.
* 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.
* 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 Modeline Specification::   The group buffer modeline.
* Group Highlighting::             Having nice colors in the group buffer.
@end menu


@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: %(%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.  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 t
Estimated total number of articles.  (This is really @var{max-number}
minus @var{min-number} plus 1.)

@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 D
Newsgroup description.

@item o
@samp{m} if moderated.

@item O
@samp{(m)} if moderated.

@item s
Select method.

@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.emacs.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 d
A string that says when you last read the group (@pxref{Group
Timestamp}). 

@item u
User defined specifier.  The next character in the format string should
be a letter.  @sc{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 Modeline Specification
@subsection Group Modeline Specification
@cindex group modeline

@vindex gnus-group-mode-line-format
The mode line can be changed by setting
@code{gnus-group-mode-line-format} (@pxref{Formatting Variables}).  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 @var{(form . 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
(setq gnus-group-highlight
      `(((> unread 200) . 
         ,(custom-face-lookup "Red" nil nil t nil nil))
        ((and (< level 3) (zerop unread)) . 
         ,(custom-face-lookup "SeaGreen" nil nil t nil nil))
        ((< level 3) . 
         ,(custom-face-lookup "SpringGreen" nil nil t nil nil))
        ((zerop unread) . 
         ,(custom-face-lookup "SteelBlue" nil nil t nil nil))
        (t . 
         ,(custom-face-lookup "SkyBlue" nil nil t nil nil))))
@end lisp

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, MAX-NUMBER minus
MIN-NUMBER.
@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}.  This hook
calls @code{gnus-group-highlight-line} by default.


@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-p
@kindex M-p (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-n
@kindex M-n (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}.


@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 @var{abs(N)} oldest articles.

@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.
This might be useful if you want to toggle threading before entering the
group.

@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 M-C-RET
@kindex M-C-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.  This is 200 by default.  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 (@code{-n}), the @code{n} oldest articles will be fetched.  If it
is positive, the @code{n} articles that have arrived most recently will
be fetched.

@vindex gnus-select-group-hook
@vindex gnus-auto-select-first
@code{gnus-auto-select-first} control whether any articles are selected
automatically when entering a group with the @kbd{SPACE} command.

@table @code

@item nil
Don't select any articles when entering the group.  Just display the
full summary buffer.

@item t
Select the first unread article when entering the group.  

@item best
Select the most high-scored article in the group when entering the
group. 
@end table
        
If you want to prevent automatic selection in some group (say, in a
binary group with Huge articles) you can set this 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

@table @kbd

@item S t
@itemx u
@kindex S t (Group)
@kindex u (Group)
@findex gnus-group-unsubscribe-current-group
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
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
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 @sc{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 on between levels 1 and
@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 (default 9),
completely dead.  Gnus treats subscribed and unsubscribed groups exactly
the same, but zombie and killed groups have no information on what
articles you have read, etc, stored.  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).

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 legal ranges.

@vindex gnus-keep-same-level
If @code{gnus-keep-same-level} is non-@code{nil}, some movement commands
will only move to groups that are 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.

@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.

@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 groups that are 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

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 assign a score to each
group.  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

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.

@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 @sc{nntp} groups, @pxref{Browse Foreign Server}.

@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 legal only on some
groups---mail groups mostly.  This command might very well be quite slow
on some backends.

@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 a
@kindex G a (Group)
@cindex (ding) archive
@cindex archive group
@findex gnus-group-make-archive-group
@vindex gnus-group-archive-directory
@vindex gnus-group-recent-archive-directory
Make a Gnus archive group (@code{gnus-group-make-archive-group}).  By
default a group pointing to the most recent articles will be created
(@code{gnus-group-recent-archive-directory}), but given a prefix, a full
group will be created from @code{gnus-group-archive-directory}.

@item G k
@kindex G k (Group)
@findex gnus-group-make-kiboze-group
@cindex nnkiboze
Make a kiboze group.  You will be prompted for a name, for a regexp to
match groups to be ``included'' in the kiboze group, and a series of
strings to match on headers (@code{gnus-group-make-kiboze-group}).
@xref{Kibozed Groups}.

@item G D
@kindex G D (Group)
@findex gnus-group-enter-directory
@cindex nneething
Read an arbitrary directory as if with were a newsgroup with the
@code{nneething} backend (@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{babyl}, @code{mbox}, @code{digest},
@code{mmdf}, @code{news}, @code{rnews}, @code{clari-briefs},
@code{rfc934}, @code{rfc822-forward}, and @code{forward}.  If you run
this command without a prefix, Gnus will guess at the file type.
@xref{Document Groups}.

@item G w
@kindex G w (Group)
@findex gnus-group-make-web-group
@cindex DejaNews
@cindex Alta Vista
@cindex InReference
@cindex nnweb
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.  Legal search engine types
include @code{dejanews}, @code{altavista} and @code{reference}.
@xref{Web Searches}.

@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.

@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 @sc{nntp} servers.


@node Group Parameters
@section Group Parameters
@cindex group parameters

The group parameters store information local to a particular group:

@table @code
@item to-address
@cindex to-address
If the group parameter list contains an element that looks like
@code{(to-address .  "some@@where.com")}, that address will be used by
the backend when doing followups and posts.  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. 

@item to-list
@cindex to-list
If the group parameter list has an element that looks like
@code{(to-list . "some@@where.com")}, that address will be used when
doing a @kbd{a} in any group.  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 don't have a
@code{to-list} group parameter, one will be added automatically upon
sending the message.

@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.  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.  This 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 this symbol is present 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 this symbol is present in the group parameter list and set to
@code{t}, new composed messages will be @code{Gcc}'d to the current
group. If it is present and set to @code{none}, no @code{Gcc:} header
will be generated, if it is present and a string, this string will be
inserted literally as a @code{gcc} header (this symbol takes precedence over
any default @code{Gcc} rules as described later).

@item auto-expire
@cindex auto-expire
If the group parameter has an element that looks like @code{(auto-expire
. t)}, , all articles that are read will be marked as expirable.  For an
alternative approach, @pxref{Expiring Mail}.

@item total-expire
@cindex total-expire
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.

@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} 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 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.  This
means that all score commands you issue will end up in that 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
When unsubscribing to 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
Elements that look like @code{(display . MODE)} says which articles to
display on entering the group.  Legal values are:

@table @code
@item all
Display all articles, both read and unread.

@item default
Display the default visible articles, which normally includes unread and
ticked articles.
@end table

@item comment
Elements that look like @code{(comment . "This is a comment")}
are arbitrary comments on the group.  They are currently ignored by
Gnus, but provide a place for you to store information on particular
groups. 

@item @var{(variable 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.

This can also be used as a group-specific hook function, if you'd like.
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.  @code{dummy-variable} will be set to the result of the
@code{(ding)} form, but who cares?

@end table

Use the @kbd{G p} command to edit group parameters of a group.

Also @pxref{Topic Parameters}.

Here's an example group parameter list:

@example
((to-address . "ding@@gnus.org")
 (auto-expiry . t))
@end example


@node Listing Groups
@section Listing Groups
@cindex group listing

These commands all list various slices of the groups that are 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 that are 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 group that
don't exist (yet)---these will be listed as if they are 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}).

@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.

@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}. 

@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.


@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}). 

@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}). 

@item G S m
@kindex G S m (Group)
@findex gnus-group-sort-groups-by-method
Sort the group buffer alphabetically by backend name
(@code{gnus-group-sort-groups-by-method}). 

@end table

When given a prefix, 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 process/prefixed groups in the group buffer 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 process/prefixed groups in the group buffer 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 process/prefixed groups in the group buffer 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 process/prefixed groups in the group buffer by group score
(@code{gnus-group-sort-selected-groups-by-score}).

@item G P r
@kindex G P r (Group)
@findex gnus-group-sort-selected-groups-by-rank
Sort the process/prefixed groups in the group buffer by group rank
(@code{gnus-group-sort-selected-groups-by-rank}).

@item G P m
@kindex G P m (Group)
@findex gnus-group-sort-selected-groups-by-method
Sort the process/prefixed groups in the group buffer alphabetically by
backend name (@code{gnus-group-sort-selected-groups-by-method}).

@end table



@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}).
If given a prefix, use the @code{ask-server} method to query the server
for new groups.

@item C-c C-x
@kindex C-c C-x (Group)
@findex gnus-group-expire-articles
Run all expirable articles in the current group through the expiry
process (if any) (@code{gnus-group-expire-articles}).

@item C-c M-C-x
@kindex C-c M-C-x (Group)
@findex gnus-group-expire-all-groups
Run all 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 be 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
Unsubscribe to the current group, or, as will be the case here,
subscribe to it (@code{gnus-browse-unsubscribe-current-group}). 

@item l
@itemx q
@kindex q (Browse)
@kindex l (Browse)
@findex gnus-browse-exit
Exit browse mode (@code{gnus-browse-exit}).

@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}).
@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
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
@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.

@findex gnus-unload
@cindex unloading
If you wish to completely unload Gnus and all its adherents, you can use
the @code{gnus-unload} command.  This command is also very handy when
trying to customize meta-variables.

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!

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...  Nice tune, that...  la la la...  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:

@lisp
(add-hook 'gnus-group-mode-hook 'gnus-topic-mode)
@end lisp

@menu 
* Topic Variables::    How to customize the topics the Lisp Way.
* Topic Commands::     Interactive E-Z commands.
* 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 Variables
@subsection Topic Variables
@cindex topic variables

Now, if you select a topic, if will fold/unfold that topic, which is
really neat, I think.

@vindex gnus-topic-line-format
The topic lines themselves are created according to the
@code{gnus-topic-line-format} variable (@pxref{Formatting Variables}).
Legal 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 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.

@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 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 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 D
@kindex T D (Topic)
@findex gnus-topic-remove-group
Remove a group from the current topic (@code{gnus-topic-remove-group}).
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}). 

@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}). 

@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.

@item T TAB
@kindex T 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 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. 

@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 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 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}). 

@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}). 

@item T S m
@kindex T S m (Topic)
@findex gnus-topic-sort-groups-by-method
Sort the current topic alphabetically by backend name
(@code{gnus-topic-sort-groups-by-method}). 

@end table

@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
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

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 legal group parameters are legal topic
parameters (@pxref{Group Parameters}).  

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
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 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 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.
@end menu

@table @kbd

@item ^
@kindex ^ (Group)
@findex gnus-group-enter-server-mode
Enter the server buffer (@code{gnus-group-enter-server-mode}).
@xref{The Server Buffer}.

@item a
@kindex a (Group)
@findex gnus-group-post-news
Post an article to a group (@code{gnus-group-post-news}).  The current
group name will be used as the default.

@item m
@kindex m (Group)
@findex gnus-group-mail
Mail a message somewhere (@code{gnus-group-mail}).

@end table

Variables for the group buffer:

@table @code

@item gnus-group-mode-hook
@vindex gnus-group-mode-hook
@code{gnus-group-mode-hook} is called after the group buffer has been
created. 

@item gnus-group-prepare-hook
@vindex gnus-group-prepare-hook
@code{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-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
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 rereading of the active file(s) from the
backend(s).

@item M-g
@kindex M-g (Group)
@findex gnus-group-get-new-news-this-group
@vindex gnus-goto-next-group-when-activating
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 f
@kindex H f (Group)
@findex gnus-group-fetch-faq
@vindex gnus-group-faq-directory
@cindex FAQ
@cindex ange-ftp
Try to fetch the FAQ for the current group
(@code{gnus-group-fetch-faq}).  Gnus will try to get the FAQ from
@code{gnus-group-faq-directory}, which is usually a directory on a
remote machine.  This variable can also be a list of directories.  In
that case, giving a prefix to this command will allow you to choose
between the various sites.  @code{ange-ftp} (or @code{efs}) will be used
for fetching the file.

If fetching from the first site is unsuccessful, Gnus will attempt to go
through @code{gnus-group-faq-directory} and try to open them one by one.

@item H d
@itemx C-c C-d
@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


@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}) (@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 The Summary Buffer
@chapter The 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.

@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.
* Canceling and Superseding::   ``Whoops, I shouldn't have called him that.''
* Marking Articles::            Marking articles as read, expirable, etc.
* Limiting::                    You can limit the summary buffer.
* Threading::                   How threads are made.
* Sorting::                     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.
* 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.
* 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.
* Crosspost Handling::          How crossposted articles are dealt with.
* Duplicate Suppression::       An alternative when crosspost handling fails.
@end menu


@node Summary Buffer Format
@section Summary Buffer Format
@cindex summary buffer format

@menu
* Summary Buffer Lines::     You can specify how summary lines should look.
* 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 function 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.

@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 @samp{}.


@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 a a normal @code{format} string, with some extensions
(@pxref{Formatting Variables}).

The default string is @samp{%U%R%z%I%(%[%4L: %-20,20n%]%) %s\n}.

The following format specification characters are understood:

@table @samp
@item N 
Article number.
@item S
Subject string.
@item s
Subject if the article is the root or the previous article had a
different subject, @code{gnus-summary-same-subject} otherwise.
(@code{gnus-summary-same-subject} defaults to @samp{}.)
@item F
Full @code{From} header.
@item n
The name (from the @code{From} header).
@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.
@item I
Indentation based on thread level (@pxref{Customizing Threading}).
@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.
@item R
Replied.
@item i
Score as a number.
@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-level} 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 @code{YYYYMMDDTHHMMSS} 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 u
User defined specifier.  The next character in the format string should
be a letter.  @sc{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 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

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 illegal 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 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.  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 V
Gnus version.
@item U
Number of unread articles in this group.
@item e
Number of unselected articles in this group.
@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.
@item s
Name of the current score file.
@item d
Number of dormant articles.
@item t
Number of ticked 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) that is 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 on the format @var{(FORM . 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 j
@itemx j
@kindex j (Summary)
@kindex G j (Summary)
@findex gnus-summary-goto-article
Ask for an article number and then go to that article
(@code{gnus-summary-goto-article}). 

@item G g
@kindex G g (Summary)
@findex gnus-summary-goto-subject
Ask for an article number and then go 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, no matter whether it has any unread articles or not.  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}).)  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.

@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.

@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}).

@item G n
@itemx n
@kindex n (Summary)
@kindex G n (Summary)
@findex gnus-summary-next-unread-article
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
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 article with the highest score
(@code{gnus-summary-best-unread-article}). 

@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 p
@kindex G p (Summary)
@findex gnus-summary-pop-article
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.
@end table


@node Choosing Variables
@subsection Choosing Variables

Some variables that are 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.  By default it
exposes any threads hidden under the selected article.

@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-unread-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}).

@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 A g
@itemx g
@kindex A g (Summary)
@kindex g (Summary)
@findex gnus-summary-show-article
(Re)fetch the current article (@code{gnus-summary-show-article}).  If
given a prefix, fetch the current article, but don't run any of the
article treatment functions.  This will give you a ``raw'' article, just
the way it came from the server.

@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}). 

@end table


@node Reply Followup and Post
@section Reply, Followup and Post

@menu
* Summary Mail Commands::            Sending mail.
* Summary Post Commands::            Sending news.
@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
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
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}). 

@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-reply-with-original}).  This command uses
the process/prefix convention.

@item S o m
@kindex S o m (Summary)
@findex gnus-summary-mail-forward
Forward the current article to some other person
(@code{gnus-summary-mail-forward}).  If given a prefix, include the full
headers of the forwarded article.

@item S m
@itemx m
@kindex m (Summary)
@kindex S m (Summary)
@findex gnus-summary-mail-other-window
Send a mail to some other person
(@code{gnus-summary-mail-other-window}).

@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 O m
@kindex S O m (Summary)
@findex gnus-uu-digest-mail-forward
Digest the current series 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 agains 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


@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
Post an article to the current group
(@code{gnus-summary-post-news}).

@item S f
@itemx f
@kindex f (Summary)
@kindex S f (Summary)
@findex 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)
@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
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 given a prefix, include the full
headers of the forwarded article.

@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-mail-forward}).  This command uses the
process/prefix convention.

@item S u
@kindex S u (Summary)
@findex 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


@node Canceling and Superseding
@section 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)
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. 

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.

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 @code{*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 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.

@menu
* Unread Articles::      Marks for unread articles.
* Read Articles::        Marks for read articles.
* Other Marks::          Marks that do not affect readedness.
@end menu

@ifinfo
There's a plethora of commands for manipulating these marks:
@end ifinfo

@menu
* Setting Marks::           How to set and remove marks.
* 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, 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.

@item SPACE
@vindex gnus-unread-mark
Markes 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 a too low 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 F
@vindex gnus-souped-mark
@sc{SOUP}ed article (@code{gnus-souped-mark}).  @xref{SOUP}.

@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-duplicated-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 the expiring of news articles, but in mail groups, for instance,
articles that are 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-cached-mark
Articles that are stored in the article cache will be marked with an
@samp{*} in the second column (@code{gnus-cached-mark}).

@item 
@vindex gnus-saved-mark
Articles that are ``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-not-empty-thread-mark
@vindex gnus-empty-thread-mark
It 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 t
@itemx !
@kindex ! (Summary)
@kindex M t (Summary)
@findex gnus-summary-tick-article-forward
Tick the current article (@code{gnus-summary-tick-article-forward}).

@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}).

@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
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
(@code{gnus-summary-catchup-to-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 c
@itemx M-u
@kindex M c (Summary)
@kindex M-u (Summary)
@findex gnus-summary-clear-mark-forward
Clear all readedness-marks from the current article
(@code{gnus-summary-clear-mark-forward}).

@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 Setting Process Marks
@subsection Setting Process Marks
@cindex setting process marks

@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 by a regular expression (@code{gnus-uu-mark-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 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-series}).

@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


@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. 

@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}). 

@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}).

@item / u
@itemx x
@kindex / u (Summary)
@kindex x (Summary)
@findex gnus-summary-limit-to-unread
Limit the summary buffer to articles that are not marked as read
(@code{gnus-summary-limit-to-unread}).  If given a prefix, limit the
buffer to articles that are 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 not 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 that are
older than (or equal to) that number of days
(@code{gnus-summary-limit-to-marks}).  If given a prefix, limit to
articles that are younger than that number of days.

@item / n
@kindex / n (Summary)
@findex gnus-summary-limit-to-articles
Limit the summary buffer to the current article
(@code{gnus-summary-limit-to-articles}).  Uses the process/prefix
convention (@pxref{Process/Prefix}).

@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 / 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 / E
@itemx M S
@kindex M S (Summary)
@kindex / E (Summary)
@findex gnus-summary-limit-include-expunged
Display all expunged articles
(@code{gnus-summary-limit-include-expunged}). 

@item / D
@kindex / D (Summary)
@findex gnus-summary-limit-include-dormant
Display all dormant articles (@code{gnus-summary-limit-include-dormant}).

@item / d
@kindex / d (Summary)
@findex gnus-summary-limit-exclude-dormant
Hide all dormant articles (@code{gnus-summary-limit-exclude-dormant}).

@item / c
@kindex / c (Summary)
@findex gnus-summary-limit-exclude-childless-dormant
Hide all dormant articles that have no children
(@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.

@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.

@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
@cindex <
@cindex >

@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-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 that are 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 backend you are using carries
overview files---this would normally be @code{nntp}, @code{nnspool} and
@code{nnml}.  Also remember that if the root of the thread has been
expired by the server, there's not much Gnus can do about that.

@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
articles that belong in the same thread together.  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-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 subjects 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-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 includes unrelated
articles, but it's 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

@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:

@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
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}.

@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-thread-hide-subtree
@vindex gnus-thread-hide-subtree
If non-@code{nil}, all threads will be hidden when the summary buffer is
generated.

@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}, the subject change is ignored.  If it
is @code{nil}, which is the default, 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-parse-headers-hook
@vindex gnus-parse-headers-hook
Hook run before parsing any headers.  The default value is
@code{(gnus-decode-rfc1522)}, which means that QPized headers will be
slightly decoded in a hackish way.  This is likely to change in the
future when Gnus becomes @sc{MIME}ified.

@end table


@node Thread Commands
@subsection Thread Commands
@cindex thread commands

@table @kbd

@item T k
@itemx M-C-k
@kindex T k (Summary)
@kindex M-C-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 M-C-l
@kindex T l (Summary)
@kindex M-C-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 thread the current article is part of
(@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}.

@end table

The following commands are thread movement commands.  They all
understand the numeric prefix.

@table @kbd

@item T n
@kindex T n (Summary)
@findex gnus-summary-next-thread
Go to the next thread (@code{gnus-summary-next-thread}).

@item T p
@kindex T p (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 `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 is
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 that are fuzzily equal will be included (@pxref{Fuzzy
Matching}).


@node Sorting
@section Sorting

@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-number
@vindex gnus-thread-sort-functions
If you are using a threaded summary display, you can sort the threads by
setting @code{gnus-thread-sort-functions}, which is a list of functions.
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-subject},
@code{gnus-thread-sort-by-date}, @code{gnus-thread-sort-by-score}, and
@code{gnus-thread-sort-by-total-score}.

Each function takes two threads and return 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.  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 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
        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
      '((lambda (t1 t2) 
          (not (gnus-thread-sort-by-number t1 t2)))
        gnus-thread-sort-by-score))
@end lisp

@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-score
@findex gnus-article-sort-by-subject
@findex gnus-article-sort-by-author
@findex gnus-article-sort-by-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
is 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}, 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



@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 @sc{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 @sc{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...  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 that 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 backend will pre-fetch
the next 30 articles.  If this variable is @code{t}, the backend will
pre-fetch all the articles that it can without bound.  If it is
@code{nil}, no pre-fetching will be made.

@vindex gnus-async-prefetch-article-p
@findex gnus-async-read-p
There are probably some articles that you don't want to pre-fetch---read
articles, for instance.  Which articles to pre-fetch is controlled by
the @code{gnus-async-prefetch-article-p} variable.  This function should
return non-@code{nil} when the article in question is to be
pre-fetched.  The default is @code{gnus-async-read-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 that are
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
preferrably be short and sweet to avoid slowing down Gnus too much.
It's also probably a good idea to byte-compile things like this.

@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)}.

@vindex gnus-use-header-prefetch
If @code{gnus-use-header-prefetch} is non-@code{nil}, prefetch articles
from the next group.


@node Article Caching
@section Article Caching
@cindex article caching
@cindex caching

If you have an @emph{extremely} slow @sc{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 that are ticked or marked as dormant will then be copied
over to your local cache (@code{gnus-cache-directory}).  Whether this
cache is flat or hierarchal is controlled by the
@code{gnus-use-long-file-name} variable, as usual.

When re-select 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 that are 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, and store them in
the cache.  You should only ever, ever ever ever, use this command if 1)
your connection to the @sc{nntp} server is really, really, really slow
and 2) you have a really, really, really huge disk.  Seriously.

@vindex gnus-uncacheable-groups
It is likely that you do not want caching on some 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 the @code{gnus-uncacheable-groups} regexp to
@samp{^nnml}, for instance.  This variable is @code{nil} by
default.

@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 @sc{nov}
files, and @kbd{gnus-cache-generate-active} will (re)generate the active
file.


@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 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.  

This variable is @code{nil} by default.


@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}).

@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
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 mail format
(@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}). 

@item O f
@kindex O f (Summary)
@findex 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
@kindex O p (Summary)
@findex gnus-summary-pipe-output
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}).
@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 four 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, @dfn{babyl}.  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-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-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}.  The former creates capitalized names, and
the latter does not.

@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.
@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
@code{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}.
@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 @code{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 that are 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 toplevel 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)) ; to get a hierarchy
(setq gnus-default-article-save 'gnus-summary-save-in-file) ; 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 toplevel 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.
* Shared Articles::       Unshar articles.
* PostScript Files::      Split PostScript.
* Decoding Variables::    Variables for a happy decoding.
* Viewing Files::         You want to look at the result of the decoding?
@end menu

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 nonstandard, 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
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 Shared Articles
@subsection Shared Articles
@cindex unshar
@cindex shared articles

@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 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 on 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 @samp{.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 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 @sc{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 @sc{mime} package (yet), so this is slightly
kludgey.

@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 articles that were
unsuccessfully decoded 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-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 @sc{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 RFC1153---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 are 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...) 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 are 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 niced.
* Article Hiding::          You also want to make certain info go away.
* Article Washing::         Lots of way-neat functions to make life better.
* Article Buttons::         Click on URLs, Message-IDs, addresses and the like.
* Article Date::            Grumble, UT!
* Article Signature::       What is a signature?
@end menu


@node Article Highlighting
@subsection Article Highlighting
@cindex highlight

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
Highlight the current article (@code{gnus-article-highlight}).

@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 @var{(regexp
name content)}.  @var{regexp} is a regular expression for matching the
header, @var{name} is the face used for highlighting the header name 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 if bigger than this variable (which is 25000 by
default), no citation highlighting will be performed.  

@item gnus-cite-prefix-regexp
@vindex gnus-cite-prefix-regexp
Regexp matching the longest possible citation prefix on a line. 

@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.  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.

@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


@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*}.  Gnus can make this look nicer by
running the article through the @kbd{W e}
(@code{gnus-article-emphasize}) command.

@vindex gnus-article-emphasis
How the emphasis is computed is controlled by the
@code{gnus-article-emphasis} 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 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-article-emphasis
      '(("_\\(\\w+\\)_" 0 1 gnus-emphasis-underline)
        ("\\*\\(\\w+\\)\\*" 0 1 gnus-emphasis-bold)))
@end lisp

@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-undeline-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


@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 maximum hiding on the summary buffer (@kbd{gnus-article-hide}). 

@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 p
@kindex W W p (Summary)
@findex gnus-article-hide-pgp
@vindex gnus-article-hide-pgp-hook
Hide @sc{pgp} signatures (@code{gnus-article-hide-pgp}).  The
@code{gnus-article-hide-pgp-hook} hook will be run after a @sc{pgp}
signature has been hidden.

@item W W P
@kindex W W P (Summary)
@findex gnus-article-hide-pem
Hide @sc{pem} (privacy enhanced messages) gruft
(@code{gnus-article-hide-pem}).

@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-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 be have at least this length (default 10) before it
is hidden.

@item gnus-cited-text-button-line-format
@vindex gnus-cited-text-button-line-format
Gnus adds buttons show where the cited text has been hidden, and to
allow toggle hiding the text.  The format of the variable is specified
by this format-like variable (@pxref{Formatting Variables}).  These
specs are legal:

@table @samp
@item b
Start point of the hidden text.
@item e
End point of the hidden text.
@item l
Length of the 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. 

@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
in @code{gnus-article-display-hook} (@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.


@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.

@table @kbd

@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}).

@item W r
@kindex W r (Summary)
@findex gnus-summary-caesar-message
Do a Caesar rotate (rot13) on the article buffer
(@code{gnus-summary-caesar-message}). 

@item W t
@kindex W 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-header
Toggle whether to display all headers in the article buffer permanently
(@code{gnus-summary-verbose-header}).

@item W m
@kindex W m (Summary)
@findex gnus-summary-toggle-mime
Toggle whether to run the article through @sc{mime} before displaying
(@code{gnus-summary-toggle-mime}).

@item W o
@kindex W o (Summary)
@findex gnus-article-treat-overstrike
Treat overstrike (@code{gnus-article-treat-overstrike}).

@item W w
@kindex W w (Summary)
@findex gnus-article-fill-cited-article
Do word wrap (@code{gnus-article-fill-cited-article}).  If you use this
function in @code{gnus-article-display-hook}, it should be run fairly
late and certainly after any highlighting.

You can give the command a numerical prefix to specify the width to use
when filling.

@item W c
@kindex W c (Summary)
@findex gnus-article-remove-cr
Remove CR (@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}).

@item W f
@kindex W f (Summary)
@cindex x-face
@findex gnus-article-display-x-face
@findex gnus-article-x-face-command
@vindex gnus-article-x-face-command
@vindex gnus-article-x-face-too-ugly
Look for and display any X-Face headers
(@code{gnus-article-display-x-face}).  The command executed by this
function is given by the @code{gnus-article-x-face-command} variable.
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 the @code{gnus-article-x-face-too-ugly} (which
is a regexp) matches the @code{From} header, the face will not be shown.
The default action under Emacs is to fork off an @code{xv} to view the
face; under XEmacs the default action is to display the face before the
@code{From} header.  (It's nicer if XEmacs has been compiled with X-Face
support---that will make display somewhat faster.  If there's no native
X-Face support, Gnus will try to convert the @code{X-Face} header using
external programs from the @code{pbmplus} package and friends.)  If you
want to have this function in the display hook, it should probably come
last.

@item W b
@kindex W b (Summary)
@findex gnus-article-add-buttons
Add clickable buttons to the article (@code{gnus-article-add-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 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 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}).

@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.

Gnus adds @dfn{buttons} to certain standard references by default:
Well-formed URLs, mail addresses and Message-IDs.  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
(REGEXP BUTTON-PAR USE-P FUNCTION DATA-PAR)
@end lisp

@table @var

@item regexp
All text that match this regular expression will be considered an
external reference.  Here's a typical regexp that match embedded URLs:
@samp{<URL:\\([^\n\r>]*\\)>}. 

@item button-par
Gnus has to know which parts of the match is to be highlighted.  This is
a number that says what sub-expression of the regexp that 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.

@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
(HEADER REGEXP BUTTON-PAR USE-P FUNCTION DATA-PAR)
@end lisp

@var{header} is a regular expression.

@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.

@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 is used when the mouse cursor is over a button.

@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 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 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 possible format specs.

@item W T e
@kindex W T e (Summary)
@findex gnus-article-date-lapsed
Say how much time has (e)lapsed between the article was posted and now
(@code{gnus-article-date-lapsed}).

@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 is
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


@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
      '("^-- $"         ; The standard
        "^-- *$"        ; A common mangling
        "^-------*$"    ; Many people just use a looong 
                        ; line of dashes.  Shame!
        "^ *--------*$" ; Double-shame!
        "^________*$"   ; Underscores are also popular
        "^========*$")) ; 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. 

@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.  


@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.

@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-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-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-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-i
@kindex C-c C-s C-i (Summary)
@findex gnus-summary-sort-by-score
Sort by score (@code{gnus-summary-sort-by-score}).
@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}).


@node Finding the Parent
@section Finding the Parent
@cindex parent articles
@cindex referring articles

@findex gnus-summary-refer-parent-article
@kindex ^ (Summary)
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 @sc{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 grandgrandparent of the current article.  If you say
@kbd{-3 ^}, Gnus will only fetch the grandgrandparent of the current
article. 

@findex gnus-summary-refer-references
@kindex A R (Summary)
You can have Gnus fetch all articles mentioned in the @code{References}
header of the article by pushing @kbd{A R}
(@code{gnus-summary-refer-references}). 

@findex gnus-summary-refer-article
@kindex M-^ (Summary)
@cindex Message-ID
@cindex fetching by Message-ID
You can also ask the @sc{nntp} server 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.

The current select method will be used when fetching by
@code{Message-ID} from non-news select method, but you can override this
by giving this command a prefix.

@vindex gnus-refer-article-method
If the group you are reading is located on a backend that does not
support fetching by @code{Message-ID} very well (like @code{nnspool}),
you can set @code{gnus-refer-article-method} to an @sc{nntp} method.  It
would, perhaps, be best if the @sc{nntp} server you consult is the same
as the one that keeps the spool you are reading from updated, but that's
not really necessary.

Most of the mail backends support fetching by @code{Message-ID}, but do
not do a particularly excellent job of it.  That is, @code{nnmbox} and
@code{nnbabyl} are able to locate articles from any groups, while
@code{nnml} and @code{nnfolder} are only able to locate articles that
have been posted to the current group.  (Anything else would be too time
consuming.)  @code{nnmh} does not support this at all.


@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 the articles she
wants to read from a summary buffer.  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 makes one additional command for switching to the summary buffer
available. 

Here are the available keystrokes when using pick mode:

@table @kbd
@item .
@kindex . (Pick)
@findex gnus-summary-mark-as-processable
Pick the article on the current line
(@code{gnus-summary-mark-as-processable}).  If given a numerical prefix,
go to the article on that line and pick that article.  (The line number
is normally displayed on 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-summary-unmark-as-processable
Unpick the article (@code{gnus-summary-unmark-as-processable}). 

@item U
@kindex U (Pick)
@findex gnus-summary-unmark-all-processable
Unpick all articles (@code{gnus-summary-unmark-all-processable}). 

@item t
@kindex t (Pick)
@findex gnus-uu-mark-thread
Pick the thread (@code{gnus-uu-mark-thread}). 

@item T
@kindex T (Pick)
@findex gnus-uu-unmark-thread
Unpick the thread (@code{gnus-uu-unmark-thread}). 

@item r
@kindex r (Pick)
@findex gnus-uu-mark-region
Pick the region (@code{gnus-uu-mark-region}). 

@item R
@kindex R (Pick)
@findex gnus-uu-unmark-region
Unpick the region (@code{gnus-uu-unmark-region}). 

@item e
@kindex e (Pick)
@findex gnus-uu-mark-by-regexp
Pick articles that match a regexp (@code{gnus-uu-mark-by-regexp}). 

@item E
@kindex E (Pick)
@findex gnus-uu-unmark-by-regexp
Unpick articles that match a regexp (@code{gnus-uu-unmark-by-regexp}). 

@item b
@kindex b (Pick)
@findex gnus-uu-mark-buffer
Pick the buffer (@code{gnus-uu-mark-buffer}). 

@item B
@kindex B (Pick)
@findex gnus-uu-unmark-buffer
Unpick the buffer (@code{gnus-uu-unmark-buffer}). 

@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

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 than 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
In fact, the only way to see the actual articles if you have turned this
mode on is the @kbd{g} command (@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.  The default
is @samp{Gnus: %%b [%A] %Z}.  For a list of legal 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.

Legal 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 @var{((real-open . real-close)
(sparse-open . sparse-close) (dummy-open . dummy-close))}, 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 that are displayed next to it.

@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 and 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
@{***@}
  |--------------------------\-----\-----\
(***)                         [Bjo] [Gun] [Gun]
  |--\-----\-----\                          |
[odd] [Jan] [odd] (***)                   [Jor]
  |           |     |--\
[Gun]       [Eri] [Eri] [odd]
                          |
                        [Paa]
@end example


@node Mail Group Commands
@section Mail Group Commands
@cindex mail group commands

Some commands only make sense in mail groups.  If these commands are
illegal 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
Expire all expirable articles in the group
(@code{gnus-summary-expire-articles}).

@item B M-C-e
@kindex B M-C-e (Summary)
@findex gnus-summary-expire-articles-now
Delete all the expirable articles in the group
(@code{gnus-summary-expire-articles-now}).  This means that @strong{all}
articles that are 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)
@findex gnus-summary-delete-article
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
Move the article from one mail group to another
(@code{gnus-summary-move-article}). 

@item B c
@kindex B c (Summary)
@cindex copy mail
@findex gnus-summary-copy-article
Copy the article from one group (mail group or not) to a mail group
(@code{gnus-summary-copy-article}).

@item B C
@kindex B C (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 r
@kindex B r (Summary)
@findex gnus-summary-respool-article
Respool the mail article (@code{gnus-summary-move-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.

@item B w
@itemx e
@kindex B w (Summary)
@kindex e (Summary)
@findex gnus-summary-edit-article
@kindex C-c C-c (Article)
Edit the current article (@code{gnus-summary-edit-article}).  To finish
editing and make the changes permanent, type @kbd{C-c C-c}
(@kbd{gnus-summary-edit-article-done}).

@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 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.

@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.

@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::       (Re)generating the summary buffer.
* Really Various Summary Commands::   Those pesky non-conformant commands.
@end menu

@table @code
@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
has been set.

@vindex gnus-summary-prepare-hook
@item gnus-summary-prepare-hook
Is 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-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.

@end table


@node Summary Group Information
@subsection Summary Group Information

@table @kbd

@item H f
@kindex H f (Summary)
@findex gnus-summary-fetch-faq
@vindex gnus-group-faq-directory
Try to fetch the FAQ (list of frequently asked questions) for the
current group (@code{gnus-summary-fetch-faq}).  Gnus will try to get the
FAQ from @code{gnus-group-faq-directory}, which is usually a directory
on a remote machine.  This variable can also be a list of directories.
In that case, giving a prefix to this command will allow you to choose
between the various sites.  @code{ange-ftp} probably will be used for
fetching the file.

@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 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 articles for a regexp
(@code{gnus-summary-search-article-backward}). 

@item &
@kindex & (Summary)
@findex gnus-summary-execute-command
This command will prompt you for a header field, a regular expression to
match on this field, and a command to be executed if the match is made
(@code{gnus-summary-execute-command}).

@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}).

@end table


@node Really Various Summary Commands
@subsection Really Various Summary Commands

@table @kbd

@item C-d
@kindex C-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 on
some format, you @kbd{C-d} and read these messages in a more convenient
fashion.

@item M-C-d
@kindex M-C-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. 

@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 q
@kindex Z Z (Summary)
@kindex q (Summary)
@findex gnus-summary-exit
@vindex gnus-summary-exit-hook
@vindex gnus-summary-prepare-exit-hook
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, and calls
@code{gnus-summary-expire-articles} by default.
@code{gnus-summary-exit-hook} is called after finishing the exiting
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
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 R
@kindex Z R (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
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.  

@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 @samp{*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.  You may want to try NoCeM handling to filter out spam
(@pxref{NoCeM}). 

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 @sc{nov}
One thing that may cause Gnus to not do the cross-posting thing
correctly is if you use an @sc{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 @sc{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 @sc{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.

@vindex gnus-nov-is-evil
If you want Gnus to get the @code{Xref}s right all the time, you have to
set @code{gnus-nov-is-evil} to @code{t}, which slows things down
considerably.

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 satisfactorily for some users for various
reasons.  

@enumerate
@item 
The @sc{nntp} server may fail to generate the @code{Xref} header.  This
is evil and not very common.

@item 
The @sc{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 @sc{nntp} servers.

@item
You may be getting mail that duplicates articles posted to groups.
@end enumerate

I'm sure there are other situations that @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 the 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 that is read in a
single Gnus session are suppressed.  

@item gnus-duplicate-list-length
@vindex gnus-duplicate-list-length
This variables 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.  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 The Article Buffer
@chapter The 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 @sc{mime} before reading them.
* 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 nauseum---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 that are 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 that are 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 that
are listed in this variable.

@findex gnus-article-hide-boring-headers
@vindex gnus-article-display-hook
@vindex gnus-boring-article-headers
You can hide further boring headers by entering
@code{gnus-article-hide-boring-headers} into
@code{gnus-article-display-hook}.  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 is 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 newsgroups
Remove the @code{Newsgroups} header if it only contains the current group
name. 
@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 address as the
@code{From} header.
@item date
Remove the @code{Date} header if the article is less than three days
old. 
@end table

To include the four first elements, you could say something like;

@lisp
(setq gnus-boring-article-headers 
      '(empty newsgroups followup-to reply-to))
@end lisp

This is also the default value for this variable.


@node Using MIME
@section Using @sc{mime}
@cindex @sc{mime}

Mime is a standard for waving your hands through the air, aimlessly,
while people stand around yawning.

@sc{mime}, however, is a standard for encoding your articles, aimlessly,
while all newsreaders die of fear.

@sc{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-show-mime
@vindex gnus-show-mime-method
@vindex gnus-strict-mime
@findex metamail-buffer
Gnus handles @sc{mime} by pushing the articles through
@code{gnus-show-mime-method}, which is @code{metamail-buffer} by
default.  Set @code{gnus-show-mime} to @code{t} if you want to use
@sc{mime} all the time.  However, if @code{gnus-strict-mime} is
non-@code{nil}, the @sc{mime} method will only be used if there are
@sc{mime} headers in the article.  If you have @code{gnus-show-mime}
set, then you'll see some unfortunate display glitches in the article
buffer.  These can't be avoided.

It might be best to just use the toggling functions from the summary
buffer to avoid getting nasty surprises. (For instance, you enter the
group @samp{alt.sing-a-long} and, before you know it, @sc{mime} has
decoded the sound file in the article and some horrible sing-a-long song
comes streaming out 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.


@node Customizing Articles
@section Customizing Articles
@cindex article customization

@vindex gnus-article-display-hook
The @code{gnus-article-display-hook} is called after the article has
been inserted into the article buffer.  It is meant to handle all
treatment of the article before it is displayed. 

@findex gnus-article-maybe-highlight
By default this hook just contains @code{gnus-article-hide-headers},
@code{gnus-article-treat-overstrike}, and
@code{gnus-article-maybe-highlight}, but there are thousands, nay
millions, of functions you can put in this hook.  For an overview of
functions @pxref{Article Highlighting}, @pxref{Article Hiding},
@pxref{Article Washing}, @pxref{Article Buttons} and @pxref{Article
Date}.  Note that the order of functions in this hook might affect
things, so you may have to fiddle a bit to get the desired results. 

You can, of course, write your own functions.  The functions are called
from the article buffer, 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.  However, you shouldn't delete any headers.  Instead
make them invisible if you want to make them go away.


@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.

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}).

@item DEL
@kindex DEL (Article)
@findex gnus-article-prev-page
Scroll backwards one page (@code{gnus-article-prev-page}).

@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{r}, 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}.  

@end table


@node Misc Article
@section Misc Article

@table @code

@item gnus-single-article-buffer
@vindex gnus-single-article-buffer
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.

@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.

@vindex gnus-article-display-hook
@item gnus-article-display-hook
This hook is called as the last thing when displaying an article, and is
intended for modifying the contents of the buffer, doing highlights,
hiding headers, and the like.

@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-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}.  It accepts the same
format specifications as that variable, with one extension:

@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. 
@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}
(form linefeed).
@end table


@node Composing Messages
@chapter Composing Messages
@cindex reply
@cindex followup
@cindex post

@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, , Top, message, The Message
Manual}.  If you are in a foreign news group, and you wish to post the
article using the foreign server, you can give a prefix to @kbd{C-c C-c}
to make Gnus try to post using the foreign server.

@menu 
* Mail::                 Mailing and replying.
* Post::                 Posting and following up.
* Posting Server::       What server should you post via?
* Mail and Post::        Mailing and posting at the same time.
* Archived Messages::    Where Gnus stores the messages you've sent.
@c * Posting Styles::       An easier way to configure some key elements.
@c * Drafts::               Postponing messages and rejected messages.
@c * Rejected Articles::    What happens if the server doesn't like your article?
@end menu

Also see @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.

@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}.

@end table


@node Post
@section Post

Variables for composing news articles:

@table @code
@item gnus-sent-message-ids-file
@vindex gnus-sent-message-ids-file
Gnus will keep a @code{Message-ID} history file of all the mails it has
sent.  If it discovers that it has already sent a mail, it will ask the
user whether to re-send the mail.  (This is primarily useful when
dealing with @sc{soup} packets and the like where one is apt to sent the
same packet multiple times.)  This variable says what the name of this
history file is.  It is @file{~/News/Sent-Message-IDs} by default.  Set
this variable to @code{nil} if you don't want Gnus to keep a history
file.

@item gnus-sent-message-ids-length
@vindex gnus-sent-message-ids-length
This variable says how many @code{Message-ID}s to keep in the history
file.  It is 1000 by default.

@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.

@vindex gnus-post-method

It can be quite complicated.  Normally, Gnus will use the same native
server.  However.  If your native server 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 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. 


@node Mail and Post
@section Mail and Post

Here's a list of variables that are 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 that are
gatewayed to the @sc{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 match 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.

@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


@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}, which
is the default.

@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:

@lisp
(nnfolder "archive"
          (nnfolder-directory "~/Mail/archive/"))
@end lisp

You can, however, use any mail select method (@code{nnml},
@code{nnmbox}, etc.).  @code{nnfolder} is a quite likeable 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:

@itemize @bullet
@item a string
Messages will be saved in that group.
@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.  This is the default.
@end itemize

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" (current-time))))))
@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.

That's the default method of archiving sent messages.  Gnus also a
different way for the people who don't like the default method.  In that
case you should set @code{gnus-message-archive-group} to @code{nil};
this will disable archiving.

XEmacs 19.13 doesn't have @code{format-time-string}, so you'll have to
use a different value for @code{gnus-message-archive-group} there.

@table @code
@item gnus-outgoing-message-group 
@vindex gnus-outgoing-message-group 
All outgoing messages will be put in this group.  If you want to store
all your outgoing mail and articles in the group @samp{nnml:archive},
you set this variable to that value.  This variable can also be a list of
group names.

If you want to have greater control over what group to put each
message in, you can set this variable to a function that checks the
current newsgroup name and then returns a suitable group name (or list
of names).

This variable can be used instead of @code{gnus-message-archive-group},
but the latter is the preferred method.
@end table


@c @node Posting Styles
@c @section Posting Styles
@c @cindex posting styles
@c @cindex styles
@c 
@c All them variables, they make my head swim.  
@c 
@c So what if you want a different @code{Organization} and signature based
@c on what groups you post to?  And you post both from your home machine
@c and your work machine, and you want different @code{From} lines, and so
@c on? 
@c 
@c @vindex gnus-posting-styles
@c One way to do stuff like that is to write clever hooks that change the
@c variables you need to have changed.  That's a bit boring, so somebody
@c came up with the bright idea of letting the user specify these things in
@c a handy alist.  Here's an example of a @code{gnus-posting-styles}
@c variable: 
@c 
@c @lisp
@c ((".*" 
@c   (signature . "Peace and happiness")
@c   (organization . "What me?"))
@c  ("^comp" 
@c   (signature . "Death to everybody"))
@c  ("comp.emacs.i-love-it" 
@c   (organization . "Emacs is it")))
@c @end lisp
@c 
@c As you might surmise from this example, this alist consists of several
@c @dfn{styles}.  Each style will be applicable if the first element
@c ``matches'', in some form or other.  The entire alist will be iterated
@c over, from the beginning towards the end, and each match will be
@c applied, which means that attributes in later styles that match override
@c the same attributes in earlier matching styles.  So
@c @samp{comp.programming.literate} will have the @samp{Death to everybody}
@c signature and the @samp{What me?} @code{Organization} header.
@c 
@c The first element in each style is called the @code{match}.  If it's a
@c string, then Gnus will try to regexp match it against the group name.
@c If it's a function symbol, that function will be called with no
@c arguments.  If it's a variable symbol, then the variable will be
@c referenced.  If it's a list, then that list will be @code{eval}ed.  In
@c any case, if this returns a non-@code{nil} value, then the style is said
@c to @dfn{match}.
@c 
@c Each style may contain a arbitrary amount of @dfn{attributes}.  Each
@c attribute consists of a @var{(name . value)} pair.  The attribute name
@c can be one of @code{signature}, @code{organization} or @code{from}.  The
@c attribute name can also be a string.  In that case, this will be used as
@c a header name, and the value will be inserted in the headers of the
@c article.
@c 
@c The attribute value can be a string (used verbatim), a function (the
@c return value will be used), a variable (its value will be used) or a
@c list (it will be @code{eval}ed and the return value will be used).
@c 
@c So here's a new example:
@c 
@c @lisp
@c (setq gnus-posting-styles
@c       '((".*" 
@c           (signature . "~/.signature") 
@c           (from . "user@@foo (user)")
@c           ("X-Home-Page" . (getenv "WWW_HOME"))
@c           (organization . "People's Front Against MWM"))
@c         ("^rec.humor" 
@c           (signature . my-funny-signature-randomizer))
@c         ((equal (system-name) "gnarly")
@c           (signature . my-quote-randomizer))
@c         (posting-from-work-p
@c           (signature . "~/.work-signature")
@c           (from . "user@@bar.foo (user)")
@c           (organization . "Important Work, Inc"))
@c         ("^nn.+:" 
@c           (signature . "~/.mail-signature"))))
@c @end lisp

@c @node Drafts
@c @section Drafts
@c @cindex drafts
@c 
@c If you are writing a message (mail or news) and suddenly remember that
@c you have a steak in the oven (or some pesto in the food processor, you
@c craazy vegetarians), you'll probably wish there was a method to save the
@c message you are writing so that you can continue editing it some other
@c day, and send it when you feel its finished.
@c 
@c Well, don't worry about it.  Whenever you start composing a message of
@c some sort using the Gnus mail and post commands, the buffer you get will
@c automatically associate to an article in a special @dfn{draft} group.
@c If you save the buffer the normal way (@kbd{C-x C-s}, for instance), the
@c article will be saved there.  (Auto-save files also go to the draft
@c group.) 
@c 
@c @cindex nndraft
@c @vindex gnus-draft-group-directory
@c The draft group is a special group (which is implemented as an
@c @code{nndraft} group, if you absolutely have to know) called
@c @samp{nndraft:drafts}.  The variable @code{gnus-draft-group-directory}
@c controls both the name of the group and the location---the leaf element
@c in the path will be used as the name of the group.  What makes this
@c group special is that you can't tick any articles in it or mark any
@c articles as read---all articles in the group are permanently unread.
@c 
@c If the group doesn't exist, it will be created and you'll be subscribed
@c to it.
@c 
@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. 
@c 
@c @findex gnus-summary-send-draft
@c @kindex S D c (Summary)
@c When you want to continue editing the article, you simply enter the
@c draft group and push @kbd{S D c} (@code{gnus-summary-send-draft}) to do
@c that.  You will be placed in a buffer where you left off.
@c 
@c Rejected articles will also be put in this draft group (@pxref{Rejected
@c Articles}).
@c 
@c @findex gnus-summary-send-all-drafts
@c If you have lots of rejected messages you want to post (or mail) without
@c doing further editing, you can use the @kbd{S D a} command
@c (@code{gnus-summary-send-all-drafts}).  This command understands the
@c process/prefix convention (@pxref{Process/Prefix}).  
@c 
@c 
@c @node Rejected Articles
@c @section Rejected Articles
@c @cindex rejected articles
@c 
@c Sometimes a news server will reject an article.  Perhaps the server
@c doesn't like your face.  Perhaps it just feels miserable.  Perhaps
@c @emph{there be demons}.  Perhaps you have included too much cited text.
@c Perhaps the disk is full.  Perhaps the server is down.
@c 
@c These situations are, of course, totally beyond the control of Gnus.
@c (Gnus, of course, loves the way you look, always feels great, has angels
@c fluttering around inside of it, doesn't care about how much cited text
@c you include, never runs full and never goes down.)  So Gnus saves these
@c articles until some later time when the server feels better.
@c 
@c The rejected articles will automatically be put in a special draft group
@c (@pxref{Drafts}).  When the server comes back up again, you'd then
@c typically enter that group and send all the articles off.
@c 

@node Select Methods
@chapter Select Methods
@cindex foreign groups
@cindex select methods

A @dfn{foreign group} is a group that is not read by the usual (or
default) means.  It could be, for instance, a group from a different
@sc{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 backend 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 backend in question.

One could say that a select method defines a @dfn{virtual server}---so
we do just that (@pxref{The Server Buffer}).

The @dfn{name} of the group is the name the backend will recognize the
group as.

For instance, the group @samp{soc.motss} on the @sc{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}
backend just knows this group as @samp{soc.motss}.

The different methods all have their peculiarities, of course.

@menu
* The Server Buffer::     Making and editing virtual servers.
* Getting News::          Reading USENET news with Gnus.
* Getting Mail::          Reading your personal mail with Gnus.
* Other Sources::         Reading directories, files, SOUP packets.
* Combined Groups::       Combining groups into one group.
@end menu


@node The Server Buffer
@section The 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 backend 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
backend represents a virtual server.

For instance, the @code{nntp} backend may be used to connect to several
different actual @sc{nntp} servers, or, perhaps, to many different ports
on the same actual @sc{nntp} server.  You tell Gnus which backend to
use, and what parameters to set by specifying a @dfn{select method}.

These select methods specifications can sometimes become quite
complicated---say, for instance, that you want to read from the
@sc{nntp} server @samp{news.funet.fi} on port number 13, which
hangs if queried for @sc{nov} headers and has a buggy select.  Ahem.
Anyways, 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, user 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 backend 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.
@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.  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 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 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 backend that has gotten out of synch.

@end table


@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
backend, and the second is the @dfn{address}, or @dfn{name}, if you
will. 

After these two elements, there may be a arbitrary number of
@var{(variable form)} pairs.

To go back to the first example---imagine that you want to read from
port 15 from 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 backend to find out what
variables are relevant, but here's an @code{nnmh} example. 

@code{nnmh} is a mail backend 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
you 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

If you are behind a firewall and only have access to the @sc{nntp}
server from the firewall machine, you can instruct Gnus to @code{rlogin}
on the firewall machine and telnet from there to the @sc{nntp} server.
Doing this can be rather fiddly, but your virtual server definition
should probably look something like this:

@lisp
(nntp "firewall"
      (nntp-address "the.firewall.machine")
      (nntp-open-connection-function nntp-open-rlogin)
      (nntp-end-of-line "\n")
      (nntp-rlogin-parameters
       ("telnet" "the.real.nntp.host" "nntp")))
@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{nnspool} to read the cache.  You
could also use @code{nnml} or @code{nnmh}, though.

Type @kbd{a nnspool RET cache RET}.

You should now have a brand new @code{nnspool} 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
(nnspool "cache")
@end lisp

Change that to:

@lisp
(nnspool "cache"
         (nnspool-spool-directory "~/News/cache/")
         (nnspool-nov-directory "~/News/cache/")
         (nnspool-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

One sticky point when defining variables (both on backends 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 backend, see each backend'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


@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 the 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 from 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{The 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 all servers
(@code{gnus-server-remove-denials}). 

@end table


@node Getting News
@section Getting News
@cindex reading news
@cindex news backends

A newsreader is normally used for reading news.  Gnus currently provides
only two methods of getting news---it can read from an @sc{nntp} server,
or it can read from a local spool.

@menu
* NNTP::               Reading news from an @sc{nntp} server.
* News Spool::         Reading news from the local spool.
@end menu


@node NNTP
@subsection @sc{nntp}
@cindex nntp

Subscribing to a foreign group from an @sc{nntp} server is rather easy.
You just specify @code{nntp} as method and the address of the @sc{nntp}
server as the, uhm, address.

If the @sc{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 authentification
@cindex nntp authentification
@findex nntp-send-authinfo
@findex nntp-send-mode-reader
@code{nntp-server-opened-hook} is run after a connection has been made.
It can be used to send commands to the @sc{nntp} server after it has
been contacted.  By default is sends the command @code{MODE READER} to
the server with the @code{nntp-send-mode-reader} function. 

@item nntp-authinfo-function 
@vindex nntp-authinfo-function 
This function will be used to send @samp{AUTHINFO} to the @sc{nntp}
server.  Available functions include:

@table @code
@item nntp-send-authinfo
@findex nntp-send-authinfo
This function will used you current login name as the user name and will
prompt you for the password.  This is the default.

@item nntp-send-nosy-authinfo
@findex nntp-send-nosy-authinfo
This function will prompt you for both user name and password.

@item nntp-send-authinfo-from-file
@findex nntp-send-authinfo-from-file
This function will use your current login name as the user name and will
read the @sc{nntp} password from @file{~/.nntp-authinfo}.
@end table

@item nntp-server-action-alist 
@vindex nntp-server-action-alist 
This is an 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 @sc{nntp} server doesn't support @sc{nov} headers, this backend
will collect headers by sending a series of @code{head} commands.  To
speed things up, the backend 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 @sc{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} backend should wait for a
connection before giving up.  If it is @code{nil}, which is the default,
no timeouts are done.

@item nntp-command-timeout
@vindex nntp-command-timeout
@cindex PPP connections
@cindex dynamic IP addresses
If you're running Gnus on a machine that has a dynamically assigned
address, Gnus may become confused.  If the address of your machine
changes after connecting to the @sc{nntp} server, Gnus will simply sit
waiting forever for replies from the server.  To help with this
unfortunate problem, you can set this command to a number.  Gnus will
then, if it sits waiting longer than that number of seconds for a reply
from the server, shut down the connection, start a new one, and resend
the command.  This should hopefully be transparent to the user.  A
likely number is 30 seconds. 

@item nntp-retry-on-break
@vindex nntp-retry-on-break
If this variable is non-@code{nil}, you can also @kbd{C-g} if Gnus
hangs.  This will have much the same effect as the command timeout
described above.

@item nntp-server-hook
@vindex nntp-server-hook
This hook is run as the last step when connecting to an @sc{nntp}
server.

@findex nntp-open-rlogin
@findex nntp-open-telnet
@findex nntp-open-network-stream
@item nntp-open-connection-function
@vindex nntp-open-connection-function
This function is used to connect to the remote system.  Three pre-made
functions are @code{nntp-open-network-stream}, which is the default, and
simply connects to some port or other on the remote system.  The other
two are @code{nntp-open-rlogin}, which does an @samp{rlogin} on the
remote system, and then does a @samp{telnet} to the @sc{nntp} server
available there, and @code{nntp-open-telnet}, which does a @samp{telnet}
to the remote system and then another @samp{telnet} to get to the
@sc{nntp} server.

@code{nntp-open-rlogin}-related variables:

@table @code

@item nntp-rlogin-parameters
@vindex nntp-rlogin-parameters
This list will be used as the parameter list given to @code{rsh}.

@item nntp-rlogin-user-name
@vindex nntp-rlogin-user-name
User name on the remote system.

@end table

@code{nntp-open-telnet}-related variables:

@table @code
@item nntp-telnet-command
@vindex nntp-telnet-command
Command used to start @samp{telnet}.

@item nntp-telnet-switches
@vindex nntp-telnet-switches
List of strings to be used as the switches to the telnet command.

@item nntp-telnet-user-name
@vindex nntp-telnet-user-name
User name to log in on the remote system as.

@item nntp-telnet-passwd
@vindex nntp-telnet-passwd
Password to use when logging in.

@item nntp-telnet-parameters
@vindex nntp-telnet-parameters
A list of strings that will be executed as a command after logging in
via telnet.

@end table

@item nntp-end-of-line
@vindex nntp-end-of-line
String to use as end-of-line markers when talking to the @sc{nntp}
server.  This is @samp{\r\n} by default, but should be @samp{\n} when
using @code{rlogin} to talk to the server.

@item nntp-rlogin-user-name
@vindex nntp-rlogin-user-name
User name on the remote system when using the @code{rlogin} connect
function. 

@item nntp-address
@vindex nntp-address
The address of the remote system running the @sc{nntp} server.

@item nntp-port-number
@vindex nntp-port-number
Port number to connect to when using the @code{nntp-open-network-stream}
connect function.

@item nntp-buggy-select
@vindex nntp-buggy-select
Set this to non-@code{nil} if your select routine is buggy.

@item nntp-nov-is-evil 
@vindex nntp-nov-is-evil 
If the @sc{nntp} server does not support @sc{nov}, you could set this
variable to @code{t}, but @code{nntp} usually checks whether @sc{nov}
can be used automatically.

@item nntp-xover-commands
@vindex nntp-xover-commands
@cindex nov
@cindex XOVER
List of strings that are used as commands to fetch @sc{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 @sc{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 @sc{nov}
lines that you do not want, and will not use.  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.

@item nntp-prepare-server-hook
@vindex nntp-prepare-server-hook
A hook run before attempting to connect to an @sc{nntp} server.

@item nntp-warn-about-losing-connection
@vindex nntp-warn-about-losing-connection
If this variable is non-@code{nil}, some noise will be made when a
server closes connection.

@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. 

Anyways, you just specify @code{nnspool} as the method and @samp{} (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 @sc{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 path of the active file.

@item nnspool-newsgroups-file
@vindex nnspool-newsgroups-file
The path of the group descriptions file.

@item nnspool-history-file
@vindex nnspool-history-file
The path of the news history file.

@item nnspool-active-times-file
@vindex nnspool-active-times-file
The path 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 @sc{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 nil, @code{nnspool} will
load the entire file into a buffer and process it there.

@end table


@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
* Getting Started Reading Mail:: A simple cookbook example.
* Splitting Mail::               How to create mail groups.
* Mail Backend Variables::       Variables for customizing mail handling.
* Fancy Mail Splitting::         Gnus can do hairy splitting of incoming mail.
* Mail and Procmail::            Reading mail groups that procmail create.
* Incorporating Old Mail::       What about the old mail you have?
* Expiring Mail::                Getting rid of unwanted mail.
* Washing Mail::                 Removing gruft from the mail you get.
* Duplicates::                   Dealing with duplicated mail.
* Not Reading Mail::             Using mail backends for reading other files.
* Choosing a Mail Backend::      Gnus can read a variety of mail formats.
@end menu


@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 backend 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 backend), you could put the following in your @file{.gnus} file:

@lisp
(setq gnus-secondary-select-methods
      '((nnml "private")))
@end lisp

Now, the next time you start Gnus, this backend will be queried for new
articles, and it will move all the messages in your spool file to its
directory, which is @code{~/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
latter 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 Backend} and @pxref{Expiring Mail}. 


@node Splitting Mail
@subsection Splitting Mail
@cindex splitting mail
@cindex mail 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.

If the first element is the special symbol @code{junk}, then messages
that match the regexp will disappear into the aether.  Use with
extreme caution. 

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.

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 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 groups names that it
thinks should carry this mail message.

Note that the mail backends 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 backends 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 files 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
@kindex 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.

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 Backend Variables
@subsection Mail Backend Variables

These variables are (for the most part) pertinent to all the various
mail backends.

@table @code
@vindex nnmail-read-incoming-hook
@item nnmail-read-incoming-hook
The mail backends 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-spool-file
@item nnmail-spool-file
@cindex POP mail
@cindex MAILHOST
@cindex movemail
@vindex nnmail-pop-password
@vindex nnmail-pop-password-required
The backends will look for new mail in this file.  If this variable is
@code{nil}, the mail backends will never attempt to fetch mail by
themselves.  If you are using a POP mail server and your name is
@samp{larsi}, you should set this variable to @samp{po:larsi}.  If
your name is not @samp{larsi}, you should probably modify that
slightly, but you may have guessed that already, you smart & handsome
devil!  You can also set this variable to @code{pop}, and Gnus will try
to figure out the POP mail string by itself.  In any case, Gnus will
call @code{movemail} which will contact the POP server named in the
@code{MAILHOST} environment variable.  If the POP server needs a
password, you can either set @code{nnmail-pop-password-required} to
@code{t} and be prompted for the password, or set
@code{nnmail-pop-password} to the password itself.

@code{nnmail-spool-file} can also be a list of mailboxes.

Your Emacs has to have been configured with @samp{--with-pop} before
compilation.  This is the default, but some installations have it
switched off.

When you use a mail backend, 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 backend---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.

@vindex nnmail-use-procmail
@vindex nnmail-procmail-suffix
@item nnmail-use-procmail
If non-@code{nil}, the mail backends will look in
@code{nnmail-procmail-directory} for incoming mail.  All the files in
that directory that have names ending in @code{nnmail-procmail-suffix}
will be considered incoming mailboxes, and will be searched for new
mail.

@vindex nnmail-crash-box
@item nnmail-crash-box
When the mail backends read a spool file, it is first moved to this
file, which is @file{~/.gnus-crash-box} by default.  If this file
already exists, it will always be read (and incorporated) before any
other spool files.

@vindex nnmail-prepare-incoming-hook
@item nnmail-prepare-incoming-hook
This is run in a buffer that holds all the new incoming mail, and can be
used for, well, anything, really.

@vindex nnmail-split-hook
@item nnmail-split-hook
@findex article-decode-rfc1522
@findex RFC1522 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-rfc1522}
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 'gnus-pre-get-new-mail-hook 
          (lambda () (set-default-file-modes 511)))

(add-hook 'gnus-post-get-new-mail-hook 
          (lambda () (set-default-file-modes 551)))
@end lisp

@item nnmail-tmp-directory
@vindex nnmail-tmp-directory
This variable says where to move the incoming mail to while processing
it.  This is usually done in the same directory that the mail backend
inhabits (i.e., @file{~/Mail/}), but if this variable is non-@code{nil},
it will be used instead.

@item nnmail-movemail-program
@vindex nnmail-movemail-program
This program is executed to move mail from the user's inbox to her home
directory.  The default is @samp{movemail}.

This can also be a function.  In that case, the function will be called
with two parameters -- the name of the inbox, and the file to be moved
to.

@item nnmail-delete-incoming
@vindex nnmail-delete-incoming
@cindex incoming mail files
@cindex deleting incoming files
If non-@code{nil}, the mail backends will delete the temporary incoming
file after splitting mail into the proper groups.  This is @code{t} by
default.

@c This is @code{nil} by
@c default for reasons of security.

@c Since Red Gnus is an alpha release, it is to be expected to lose mail.
(No Gnus release since (ding) Gnus 0.10 (or something like that) have
lost mail, I think, but that's not the point.  (Except certain versions
of Red Gnus.))  By not deleting the Incoming* files, one can be sure to
not lose mail -- if Gnus totally whacks out, one can always recover what
was lost.

Delete the @file{Incoming*} files at will.

@item nnmail-use-long-file-names
@vindex nnmail-use-long-file-names
If non-@code{nil}, the mail backends will use long file and directory
names.  Groups like @samp{mail.misc} will end up in directories 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 backend (via @code{Gcc}, for instance) into the mail duplication
discovery cache.  The default is @code{nil}.

@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
;; Messages from the mailer daemon are not crossposted to any of
;; the ordinary groups.  Warnings are put in a separate group
;; from real errors.
(| ("from" mail (| ("subject" "warn.*" "mail.warning")
                   "mail.misc"))
   ;; Non-error messages are crossposted to all relevant
   ;; groups, but we don't crosspost between the group for the
   ;; (ding) list and the group for other (ding) related mail.
   (& (| (any "ding@@ifi\\.uio\\.no" "ding.list")
         ("subject" "ding" "ding.misc"))
      ;; Other mailing lists...
      (any "procmail@@informatik\\.rwth-aachen\\.de" "procmail.list")
      (any "SmartList@@informatik\\.rwth-aachen\\.de" "SmartList.list")
      ;; People...
      (any "larsi@@ifi\\.uio\\.no" "people.Lars_Magne_Ingebrigtsen"))
   ;; 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 five possible split syntaxes:

@enumerate

@item 
@samp{group}: If the split is a string, that will be taken as a group name. 

@item
@var{(FIELD VALUE SPLIT)}: If the split is a list, and the first
element is a string, then that means that if header FIELD (a regexp)
contains VALUE (also a regexp), then store the message as specified by
SPLIT.

@item
@var{(| SPLIT...)}: If the split is a list, and the first element is
@code{|} (vertical bar), then process each SPLIT until one of them
matches.  A SPLIT is said to match if it will cause the mail message to
be stored in one or more groups.

@item
@var{(& SPLIT...)}: If the split is a list, and the first element is
@code{&}, then process all SPLITs in the list.

@item 
@code{junk}: If the split is the symbol @code{junk}, then don't save
this message anywhere.

@item
@var{(: function arg1 arg2 ...)}:  If the split is a list, and the first
element is @code{:}, then the second element will be called as a
function with @var{args} given as arguments.  The function should return
a SPLIT.

@end enumerate

In these splits, @var{FIELD} must match a complete field name.
@var{VALUE} must match a complete word according to the fundamental mode
syntax table.  You can use @code{.*} in the regexps to match partial
field names or words.  In other words, all @var{VALUE}'s are wrapped in
@samp{\<} and @samp{\>} pairs.

@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 car of the cells contains the key, and the cdr contains a string.

@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, you can say things like:

@example
(any "debian-\(\\w*\\)@@lists.debian.org" "mail.debian.\\1")
@end example

That is, do @code{replace-match}-like substitions in the group names. 


@node Mail and Procmail
@subsection Mail and Procmail
@cindex procmail

@cindex slocal
@cindex elm
Many people use @code{procmail} (or some other mail filter program or
external delivery agent---@code{slocal}, @code{elm}, etc) to split
incoming mail into groups.  If you do that, you should set
@code{nnmail-spool-file} to @code{procmail} to ensure that the mail
backends never ever try to fetch mail by themselves.

This also means that you probably don't want to set
@code{nnmail-split-methods} either, which has some, perhaps, unexpected
side effects.

When a mail backend is queried for what groups it carries, it replies
with the contents of that variable, along with any groups it has figured
out that it carries by other means.  None of the backends (except
@code{nnmh}) actually go out to the disk and check what groups actually
exist.  (It's not trivial to distinguish between what the user thinks is
a basis for a newsgroup and what is just a plain old file or directory.)

This means that you have to tell Gnus (and the backends) what groups
exist by hand.

Let's take the @code{nnmh} backend as an example. 

The folders are located in @code{nnmh-directory}, say, @file{~/Mail/}.
There are three folders, @file{foo}, @file{bar} and @file{mail.baz}.

Go to the group buffer and type @kbd{G m}.  When prompted, answer
@samp{foo} for the name and @samp{nnmh} for the method.  Repeat
twice for the two other groups, @samp{bar} and @samp{mail.baz}.  Be sure
to include all your mail groups.

That's it.  You are now set to read your mail.  An active file for this
method will be created automatically.

@vindex nnmail-procmail-suffix
@vindex nnmail-procmail-directory
If you use @code{nnfolder} or any other backend that store more than a
single article in each file, you should never have procmail add mails to
the file that Gnus sees.  Instead, procmail should put all incoming mail
in @code{nnmail-procmail-directory}.  To arrive at the file name to put
the incoming mail in, append @code{nnmail-procmail-suffix} to the group
name.  The mail backends will read the mail from these files.

@vindex nnmail-resplit-incoming
When Gnus reads a file called @file{mail.misc.spool}, this mail will be
put in the @code{mail.misc}, as one would expect.  However, if you want
Gnus to split the mail the normal way, you could set
@code{nnmail-resplit-incoming} to @code{t}.

@vindex nnmail-keep-last-article
If you use @code{procmail} to split things directory into an @code{nnmh}
directory (which you shouldn't do), you should set
@code{nnmail-keep-last-article} to non-@code{nil} to prevent Gnus from
ever expiring the final article (i. e., the article with the highest
article number) in a mail newsgroup.  This is quite, quite important.

Here's an example setup:  The incoming spools are located in
@file{~/incoming/} and have @samp{""} as suffixes (i. e., the incoming
spool files have the same names as the equivalent groups).  The
@code{nnfolder} backend is to be used as the mail interface, and the
@code{nnfolder} directory is @file{~/fMail/}.

@lisp
(setq nnfolder-directory "~/fMail/")
(setq nnmail-spool-file 'procmail)
(setq nnmail-procmail-directory "~/incoming/")
(setq gnus-secondary-select-methods '((nnfolder "")))
(setq nnmail-procmail-suffix "")
@end lisp


@node Incorporating Old Mail
@subsection Incorporating 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
backends, 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 `G f' and give the path of the mbox file when prompted to create an
@code{nndoc} group from the mbox file (@pxref{Foreign Groups}).

@item 
Type `SPACE' to enter the newly created group.

@item
Type `M P b' to process-mark all articles in this group (@pxref{Setting
Process Marks}).

@item 
Type `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
backend to another.  Just respool all the mail in the old mail groups
using the new mail backend.


@node Expiring Mail
@subsection Expiring Mail
@cindex article expiry

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}.  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-newsgroups
You do not have to mark articles as expirable by hand.  Groups that
match the regular expression @code{gnus-auto-expirable-newsgroups} will
have all articles that you read marked as expirable automatically.  All
articles that are marked as expirable have an @samp{E} in the first
column in the summary buffer.

Note that making a group auto-expirable don't mean that all read
articles are expired---only the articles that are marked as expirable
will be expired.  Also note the using the @kbd{d} command won't make
groups 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
doesn'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 that 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 be either a number (not
necessarily an integer) or 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-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. 


@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, RFC822 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 RFC822 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 disc.  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.  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 too make them look nice.  Aaah.  

@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.

For instance, if you want to remove the @samp{(idm)} and the
@samp{nagnagnag} identifiers:

@lisp
(setq nnmail-list-identifiers
      '("(idm)" "nagnagnag"))
@end lisp

@item nnmail-remove-tabs
@findex nnmail-remove-tabs
Translate all @samp{TAB} characters into @samp{SPACE} characters. 

@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 list, you will sometime
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
      '(| ;; Messages duplicates go to a separate group.
          ("gnus-warning" "duplication of message" "duplicate")
          ;; Message from daemons, postmaster, and the like to another.
          (any mail "mail.misc")
          ;; Other rules.
          [ ... ] ))
@end lisp

Or something like:
@lisp
(setq nnmail-split-methods 
      '(("duplicates" "^Gnus-Warning:")
        ;; 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 backends, 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{nnmail-spool-file} to @code{nil}, none of the backends
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 @sc{rmail}
file you have stashed away with @code{nnbabyl}.  All backends have
variables called backend-@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 backends 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 Backend
@subsection Choosing a Mail Backend

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.

@menu
* Unix Mail Box::               Using the (quite) standard Un*x mbox.
* Rmail Babyl::                 Emacs programs use the rmail babyl format.
* Mail Spool::                  Store your mail in a private spool?
* MH Spool::                    An mhspool-like backend.
* Mail Folders::                Having one file for each group.
@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} backend 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. 

@item nnmbox-active-file
@vindex nnmbox-active-file
The name of the active file for the mail box.

@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.
@end table


@node Rmail Babyl
@subsubsection Rmail Babyl
@cindex nnbabyl
@cindex rmail mbox

@vindex nnbabyl-active-file
@vindex nnbabyl-mbox-file
The @dfn{nnbabyl} backend will use a babyl mail box (aka. @dfn{rmail
mbox}) 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 rmail mbox file.

@item nnbabyl-active-file
@vindex nnbabyl-active-file
The name of the active file for the rmail box.

@item nnbabyl-get-new-mail
@vindex nnbabyl-get-new-mail
If non-@code{nil}, @code{nnbabyl} will read incoming mail. 
@end table


@node Mail Spool
@subsubsection Mail Spool
@cindex nnml
@cindex mail @sc{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 backend, Gnus will split all incoming mail into files;
one file for each mail, and put the articles into the correct
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 backend.  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 backend when it comes to article
splitting.  It has to create lots of files, and it also generates
@sc{nov} databases for the incoming mails.  This makes is the fastest
backend 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. 

@item nnml-active-file
@vindex nnml-active-file
The active file for the @code{nnml} server.

@item nnml-newsgroups-file
@vindex nnml-newsgroups-file
The @code{nnml} group descriptions file.  @xref{Newsgroups File
Format}. 

@item nnml-get-new-mail
@vindex nnml-get-new-mail
If non-@code{nil}, @code{nnml} will read incoming mail.

@item nnml-nov-is-evil
@vindex nnml-nov-is-evil
If non-@code{nil}, this backend will ignore any @sc{nov} files.  

@item nnml-nov-file-name
@vindex nnml-nov-file-name
The name of the @sc{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.

@end table

@findex nnml-generate-nov-databases
If your @code{nnml} groups and @sc{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
@sc{nov} databases and it doesn't keep an active file.  This makes
@code{nnmh} a @emph{much} slower backend 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.

@item nnmh-get-new-mail
@vindex nnmh-get-new-mail
If non-@code{nil}, @code{nnmh} will read incoming mail.

@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}.
@end table


@node Mail Folders
@subsubsection Mail Folders
@cindex nnfolder
@cindex mbox folders
@cindex mail folders

@code{nnfolder} is a backend 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. 

@item nnfolder-active-file
@vindex nnfolder-active-file
The name of the active file.

@item nnfolder-newsgroups-file
@vindex nnfolder-newsgroups-file
The name of the group descriptions file.  @xref{Newsgroups File Format}.

@item nnfolder-get-new-mail
@vindex nnfolder-get-new-mail
If non-@code{nil}, @code{nnfolder} will read incoming mail.
@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}.


@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.
* SOUP::                  Reading @sc{SOUP} packets ``offline''.
* Web Searches::          Creating groups from articles that match a string.
* Mail-To-News Gateways:: Posting articles via mail-to-news gateways.
@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}, that most
wonderful of all wonderful Emacs packages.  When I wrote @code{nndir}, I
didn't think much about it---a backend 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 the directory name,
@code{ange-ftp} will actually allow you to read this directory over at
@samp{sina} as a newsgroup.  Distributed news ahoy!

@code{nndir} will use @sc{nov} files if they are present.

@code{nndir} is a ``read-only'' backend---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} backend (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-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
@cindex rmail mbox

@item babyl
The babyl (rmail) mail box.
@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.

@item rnews
@cindex rnews batch files
The rnews batch transport format.
@cindex forwarded messages

@item forward
Forwarded articles.

@item mime-digest
@cindex digest
@cindex MIME digest
@cindex 1153 digest
@cindex RFC 1153 digest
@cindex RFC 341 digest
MIME (RFC 1341) digest format.

@item standard-digest
The standard (RFC 1153) digest format.

@item slack-digest
Non-standard digest format---matches most things, but does it badly. 
@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 backend, @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{mmdf}, @code{forward}, @code{rfc934}, @code{rfc822-forward},
@code{news}, @code{rnews}, @code{mime-digest}, @code{clari-briefs}, 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 legal 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.

@item head-begin-function
If present, this should be a function that moves point to the head of
the article.

@item nndoc-head-begin
If present, this should be a regexp that matches the head of the
article. 

@item nndoc-head-end
This should match the end of the head of the article.  It defaults to
@samp{^$}---the empty line.

@item body-begin-function
If present, this function should move point to the beginning of the body
of the article.

@item body-begin
This should match the beginning of the body of the article.  It defaults
to @samp{^\n}.

@item body-end-function
If present, this function should move point to the end of the body of
the article.

@item body-end
If present, this should match the end of the body of the article.

@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 how 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.

@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-TYPE-type-p} is called for each
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 legal number.


@node SOUP
@subsection SOUP
@cindex SOUP
@cindex offline

In the PC world people often talk about ``offline'' newsreaders.  These
are thingies that are combined reader/news transport monstrosities.
With built-in modem programs.  Yecchh!

Of course, us Unix Weenie types of human beans use things like
@code{uucp} and, like, @code{nntpd} and set up proper news and mail
transport things like Ghod intended.  And then we just use normal
newsreaders.  

However, it can sometimes be convenient to do something a that's a bit
easier on the brain if you have a very slow modem, and you're not really
that interested in doing things properly.  

A file format called @sc{soup} has been developed for transporting news
and mail from servers to home machines and back again.  It can be a bit
fiddly.

First some terminology:

@table @dfn

@item server
This is the machine that is connected to the outside world and where you
get news and/or mail from.

@item home machine
This is the machine that you want to do the actual reading and responding
on.  It is typically not connected to the rest of the world in any way.

@item packet
Something that contains messages and/or commands.  There are two kinds
of packets:

@table @dfn
@item message packets
These are packets made at the server, and typically contains lots of
messages for you to read.  These are called @file{SoupoutX.tgz} by
default, where @var{X} is a number.

@item response packets
These are packets made at the home machine, and typically contains
replies that you've written.  These are called @file{SoupinX.tgz} by
default, where @var{X} is a number.

@end table

@end table


@enumerate

@item
You log in on the server and create a @sc{soup} packet.  You can either
use a dedicated @sc{soup} thingie (like the @code{awk} program), or you
can use Gnus to create the packet with its @sc{soup} commands (@kbd{O
s} and/or @kbd{G s b}; and then @kbd{G s p}) (@pxref{SOUP Commands}).

@item 
You transfer the packet home.  Rail, boat, car or modem will do fine.

@item
You put the packet in your home directory.

@item
You fire up Gnus on your home machine using the @code{nnsoup} backend as
the native or secondary server.

@item
You read articles and mail and answer and followup to the things you
want (@pxref{SOUP Replies}).

@item 
You do the @kbd{G s r} command to pack these replies into a @sc{soup}
packet.

@item 
You transfer this packet to the server.  

@item
You use Gnus to mail this packet out with the @kbd{G s s} command.

@item
You then repeat until you die.

@end enumerate

So you basically have a bipartite system---you use @code{nnsoup} for
reading and Gnus for packing/sending these @sc{soup} packets.

@menu
* SOUP Commands::     Commands for creating and sending @sc{soup} packets
* SOUP Groups::       A backend for reading @sc{soup} packets.
* SOUP Replies::      How to enable @code{nnsoup} to take over mail and news.
@end menu


@node SOUP Commands
@subsubsection SOUP Commands

These are commands for creating and manipulating @sc{soup} packets.

@table @kbd
@item G s b
@kindex G s b (Group)
@findex gnus-group-brew-soup
Pack all unread articles in the current group
(@code{gnus-group-brew-soup}).  This command understands the
process/prefix convention.

@item G s w
@kindex G s w (Group)
@findex gnus-soup-save-areas
Save all @sc{soup} data files (@code{gnus-soup-save-areas}).

@item G s s
@kindex G s s (Group)
@findex gnus-soup-send-replies
Send all replies from the replies packet
(@code{gnus-soup-send-replies}). 

@item G s p
@kindex G s p (Group)
@findex gnus-soup-pack-packet
Pack all files into a @sc{soup} packet (@code{gnus-soup-pack-packet}). 

@item G s r
@kindex G s r (Group)
@findex nnsoup-pack-replies
Pack all replies into a replies packet (@code{nnsoup-pack-replies}). 

@item O s
@kindex O s (Summary)
@findex gnus-soup-add-article
This summary-mode command adds the current article to a @sc{soup} packet
(@code{gnus-soup-add-article}).  It understands the process/prefix
convention (@pxref{Process/Prefix}). 

@end table


There are a few variables to customize where Gnus will put all these
thingies:  

@table @code

@item gnus-soup-directory
@vindex gnus-soup-directory
Directory where Gnus will save intermediate files while composing
@sc{soup} packets.  The default is @file{~/SoupBrew/}. 

@item gnus-soup-replies-directory
@vindex gnus-soup-replies-directory
This is what Gnus will use as a temporary directory while sending our
reply packets.  @file{~/SoupBrew/SoupReplies/} is the default.

@item gnus-soup-prefix-file
@vindex gnus-soup-prefix-file
Name of the file where Gnus stores the last used prefix.  The default is
@samp{gnus-prefix}. 

@item gnus-soup-packer
@vindex gnus-soup-packer
A format string command for packing a @sc{soup} packet.  The default is
@samp{tar cf - %s | gzip > $HOME/Soupout%d.tgz}. 

@item gnus-soup-unpacker
@vindex gnus-soup-unpacker
Format string command for unpacking a @sc{soup} packet.  The default is
@samp{gunzip -c %s | tar xvf -}.

@item gnus-soup-packet-directory
@vindex gnus-soup-packet-directory
Where Gnus will look for reply packets.  The default is @file{~/}. 

@item gnus-soup-packet-regexp
@vindex gnus-soup-packet-regexp
Regular expression matching @sc{soup} reply packets in
@code{gnus-soup-packet-directory}. 

@end table
 

@node SOUP Groups
@subsubsection @sc{soup} Groups
@cindex nnsoup

@code{nnsoup} is the backend for reading @sc{soup} packets.  It will
read incoming packets, unpack them, and put them in a directory where
you can read them at leisure.

These are the variables you can use to customize its behavior:

@table @code

@item nnsoup-tmp-directory
@vindex nnsoup-tmp-directory
When @code{nnsoup} unpacks a @sc{soup} packet, it does it in this
directory.  (@file{/tmp/} by default.)  

@item nnsoup-directory
@vindex nnsoup-directory
@code{nnsoup} then moves each message and index file to this directory.
The default is @file{~/SOUP/}.

@item nnsoup-replies-directory 
@vindex nnsoup-replies-directory 
All replies will stored in this directory before being packed into a
reply packet.  The default is @file{~/SOUP/replies/"}.

@item nnsoup-replies-format-type
@vindex nnsoup-replies-format-type
The @sc{soup} format of the replies packets.  The default is @samp{?n}
(rnews), and I don't think you should touch that variable.  I probably
shouldn't even have documented it.  Drats!  Too late!

@item nnsoup-replies-index-type
@vindex nnsoup-replies-index-type
The index type of the replies packet.  The is @samp{?n}, which means
``none''.  Don't fiddle with this one either!

@item nnsoup-active-file
@vindex nnsoup-active-file
Where @code{nnsoup} stores lots of information.  This is not an ``active
file'' in the @code{nntp} sense; it's an Emacs Lisp file.  If you lose
this file or mess it up in any way, you're dead.  The default is
@file{~/SOUP/active}.

@item nnsoup-packer
@vindex nnsoup-packer
Format string command for packing a reply @sc{soup} packet.  The default
is @samp{tar cf - %s | gzip > $HOME/Soupin%d.tgz}. 

@item nnsoup-unpacker
@vindex nnsoup-unpacker
Format string command for unpacking incoming @sc{soup} packets.  The
default is @samp{gunzip -c %s | tar xvf -}. 

@item nnsoup-packet-directory
@vindex nnsoup-packet-directory
Where @code{nnsoup} will look for incoming packets.  The default is
@file{~/}.  

@item nnsoup-packet-regexp
@vindex nnsoup-packet-regexp
Regular expression matching incoming @sc{soup} packets.  The default is
@samp{Soupout}. 

@end table


@node SOUP Replies
@subsubsection SOUP Replies

Just using @code{nnsoup} won't mean that your postings and mailings end
up in @sc{soup} reply packets automagically.  You have to work a bit
more for that to happen.

@findex nnsoup-set-variables
The @code{nnsoup-set-variables} command will set the appropriate
variables to ensure that all your followups and replies end up in the
@sc{soup} system.

In specific, this is what it does:

@lisp
(setq message-send-news-function 'nnsoup-request-post)
(setq message-send-mail-function 'nnsoup-request-mail)
@end lisp

And that's it, really.  If you only want news to go into the @sc{soup}
system you just use the first line.  If you only want mail to be
@sc{soup}ed you use the second.


@node Web Searches
@subsection Web Searches
@cindex nnweb
@cindex DejaNews
@cindex Alta Vista
@cindex InReference
@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} backend 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 (@code{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 (DejaNews, 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 that were 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.

You must have the @code{url} and @code{w3} package installed to be able
to use @code{nnweb}.

Virtual server variables:

@table @code
@item nnweb-type
@vindex nnweb-type
What search engine type is being used.  The currently supported types
are @code{dejanews}, @code{altavista} and @code{reference}.

@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
100.

@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 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} backend provides the interface.

Note that you can't read anything from this backend---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 have 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---an article with this
@code{Newsgroups} header:

@example
Newsgroups: alt.religion.emacs
@end example

will get this @code{From} header inserted:

@example
To: alt-religion-emacs@@GATEWAY
@end example

@end table

So, to use this, simply say something like:

@lisp
(setq gnus-post-method '(nngateway "GATEWAY.ADDRESS"))
@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.
* Kibozed Groups::     Looking through parts of the newsfeed for articles.
@end menu


@node Virtual Groups
@subsection Virtual Groups
@cindex nnvirtual
@cindex virtual 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 group, 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.)

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+some.server.jp:soc.motss$\\|^nntp+some.server.no:soc.motss$"
@end example

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 that are included in a virtual
group has 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} is non-@code{nil},
@code{nnvirtual} will always scan groups for unread articles when
entering a virtual group.  If this variable is @code{nil} (which is the
default) 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 contain the same component
group.  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.


@node Kibozed Groups
@subsection Kibozed Groups
@cindex nnkiboze
@cindex kibozing

@dfn{Kibozing} is defined by @sc{oed} as ``grepping through (parts of)
the news feed''.  @code{nnkiboze} is a backend that will do this for
you.  Oh joy!  Now you can grind any @sc{nntp} server down to a halt
with useless requests!  Oh happiness!

@kindex G k (Group)
To create a kibozed group, use the @kbd{G k} command in the group
buffer. 

The address field of the @code{nnkiboze} method is, as with
@code{nnvirtual}, a regexp to match groups to be ``included'' in the
@code{nnkiboze} group.  There most similarities between @code{nnkiboze}
and @code{nnvirtual} ends.

In addition to this regexp detailing component groups, an @code{nnkiboze} group
must have a score file to say what articles that are to be included in
the group (@pxref{Scoring}).

@kindex M-x nnkiboze-generate-groups
@findex nnkiboze-generate-groups
You must run @kbd{M-x nnkiboze-generate-groups} after creating the
@code{nnkiboze} groups you want to have.  This command will take time.  Lots of
time.  Oodles and oodles of time.  Gnus has to fetch the headers from
all the articles in all the components groups and run them through the
scoring process to determine if there are any articles in the groups
that are to be part of the @code{nnkiboze} groups.

Please limit the number of component groups by using restrictive
regexps.  Otherwise your sysadmin may become annoyed with you, and the
@sc{nntp} site may throw you off and never let you back in again.
Stranger things have happened.

@code{nnkiboze} component groups do not have to be alive---they can be dead,
and they can be foreign.  No restrictions.

@vindex nnkiboze-directory
The generation of an @code{nnkiboze} group means writing two files in
@code{nnkiboze-directory}, which is @file{~/News/} by default.  One
contains the @sc{nov} header lines for all the articles in the group,
and the other is an additional @file{.newsrc} file to store information
on what groups that have been searched through to find component
articles.

Articles that are marked as read in the @code{nnkiboze} group will have their
@sc{nov} lines removed from the @sc{nov} file.


@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 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.
* GroupLens::                Getting predictions on what you like to read.
* 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}).   

@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 a
@kindex V a (Summary)
@findex gnus-summary-score-entry
Add a new score entry, and allow specifying all elements 
(@code{gnus-summary-score-entry}).

@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}). 

@item I C-i
@kindex I C-i (Summary)
@findex gnus-summary-raise-score
Increase the score of the current article
(@code{gnus-summary-raise-score}).

@item L C-l
@kindex L C-l (Summary)
@findex gnus-summary-lower-score
Lower the score of the current article
(@code{gnus-summary-lower-score}). 
@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.)  

@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 Xref line---i.e., the cross-posting line.

@item t
Score on thread---the References line.

@item d
Score on the date.

@item l
Score on the number of lines.

@item i
Score on the Message-ID.

@item f
Score on followups.

@item b
Score on the body.

@item h
Score on the head.
@end table

@item
The third key is the match type.  Which match types are legal 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
At 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 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

@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}.

@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 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


@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 @code{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
(@samp{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, if this might make you Emacs grow big and
bloated, so this regexp can be used to weed out score files that are
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.

@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.

@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}.

@end table
This variable can also be a list of functions.  In that case, all these
functions will be called, and all the returned lists of score files will
be applied.  These functions can also return 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.

@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}, matching score entries will have
their dates updated.  (This is how Gnus controls expiry---all
non-matching entries will become too old while matching entries will
stay fresh and young.)  However, if you set this variable to @code{nil},
even matching 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.

@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.  For a different
approach, see @pxref{Advanced Scoring}.

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 legal 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 a 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 Lines, Chars
These two headers use different match types: @code{<}, @code{>},
@code{=}, @code{>=} and @code{<=}.  When matching on @code{Lines}, be
careful because some backends (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---@samp{YYYYMMDDTHHMMSS}.  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 e.g. 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 that is
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
undeterministic scores of the articles in the thread.  (Using this match
key will lead to creation of @file{ADAPT} files.)
@end table
@end enumerate

@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}el.  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}).

@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 there
exist a few interesting threads which can't be found automatically by
ordinary scoring rules.

@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 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.
@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-done
Save the changes you have made and return to the summary buffer
(@code{gnus-score-edit-done}). 

@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} and @kbd{V
e} 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
(defvar 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{D}) 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.  

You can also score on @code{thread}, which will try to score all
articles that appear in a thread.  @code{thread} matches uses a
@code{Message-ID} to match on the @code{References} header of the
article.  If the match is made, the @code{Message-ID} of the article is
added to the @code{thread} rule.  (Think about it.  I'd recommend two
aspirins afterwards.)

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 @samp{ADAPT}.

@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 that are 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-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.

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 
@var{(regexp file-name)}.  If the @var{regexp} matches the group name,
the @var{file-name} will will be used as the home score file.

@item 
A function. If the function returns non-nil, the result will be used as
the home score file.

@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:

@lisp
(setq gnus-home-score-file
      'gnus-hierarchial-home-score-file)
@end lisp

This is a ready-made function provided for your convenience.

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
      ;; All groups that match the regexp "\\.emacs"
      '("\\.emacs" "emacs.SCORE")
      ;; 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}.  

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 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 has a score 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.

Say you want 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:

@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
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 that are 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

... 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 them 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 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 called just @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 Gnus by default.
You can fetch it from
@file{http://www.ifi.uio.no/~larsi/ding-other/gnus-kill-to-score}.  

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 GroupLens
@section GroupLens
@cindex GroupLens

GroupLens is a collaborative filtering system that helps you work
together with other people to find the quality news articles out of the
huge volume of news articles generated every day.

To accomplish this the GroupLens system combines your opinions about
articles you have already read with the opinions of others who have done
likewise and gives you a personalized prediction for each unread news
article.  Think of GroupLens as a matchmaker.  GroupLens watches how you
rate articles, and finds other people that rate articles the same way.
Once it has found for you some people you agree with it tells you, in
the form of a prediction, what they thought of the article.  You can use
this prediction to help you decide whether or not you want to read the
article.

@menu
* Using GroupLens::          How to make Gnus use GroupLens.
* Rating Articles::          Letting GroupLens know how you rate articles.
* Displaying Predictions::   Displaying predictions given by GroupLens.
* GroupLens Variables::      Customizing GroupLens.
@end menu


@node Using GroupLens
@subsection Using GroupLens

To use GroupLens you must register a pseudonym with your local Better
Bit Bureau (BBB).
@samp{http://www.cs.umn.edu/Research/GroupLens/bbb.html} is the only
better bit in town is at the moment.

Once you have registered you'll need to set a couple of variables.

@table @code

@item gnus-use-grouplens
@vindex gnus-use-grouplens
Setting this variable to a non-@code{nil} value will make Gnus hook into
all the relevant GroupLens functions.

@item grouplens-pseudonym
@vindex grouplens-pseudonym
This variable should be set to the pseudonym you got when registering
with the Better Bit Bureau.

@item grouplens-newsgroups
@vindex grouplens-newsgroups
A list of groups that you want to get GroupLens predictions for. 

@end table

Thats the minimum of what you need to get up and running with GroupLens.
Once you've registered, GroupLens will start giving you scores for
articles based on the average of what other people think.  But, to get
the real benefit of GroupLens you need to start rating articles
yourself.  Then the scores GroupLens gives you will be personalized for
you, based on how the people you usually agree with have already rated.


@node Rating Articles
@subsection Rating Articles

In GroupLens, an article is rated on a scale from 1 to 5, inclusive.
Where 1 means something like this article is a waste of bandwidth and 5
means that the article was really good.  The basic question to ask
yourself is, "on a scale from 1 to 5 would I like to see more articles
like this one?"

There are four ways to enter a rating for an article in GroupLens.

@table @kbd

@item r
@kindex r (GroupLens)
@findex bbb-summary-rate-article
This function will prompt you for a rating on a scale of one to five.

@item k
@kindex k (GroupLens)
@findex grouplens-score-thread
This function will prompt you for a rating, and rate all the articles in
the thread.  This is really useful for some of those long running giant
threads in rec.humor.

@end table

The next two commands, @kbd{n} and @kbd{,} take a numerical prefix to be
the score of the article you're reading.

@table @kbd

@item 1-5 n
@kindex n (GroupLens)
@findex grouplens-next-unread-article
Rate the article and go to the next unread article.

@item 1-5 ,
@kindex , (GroupLens)
@findex grouplens-best-unread-article
Rate the article and go to the next unread article with the highest score.

@end table

If you want to give the current article a score of 4 and then go to the
next article, just type @kbd{4 n}.


@node Displaying Predictions
@subsection Displaying Predictions

GroupLens makes a prediction for you about how much you will like a
news article.  The predictions from GroupLens are on a scale from 1 to
5, where 1 is the worst and 5 is the best.  You can use the predictions
from GroupLens in one of three ways controlled by the variable
@code{gnus-grouplens-override-scoring}.

@vindex gnus-grouplens-override-scoring
There are three ways to display predictions in grouplens.  You may
choose to have the GroupLens scores contribute to, or override the
regular gnus scoring mechanism. override is the default; however, some
people prefer to see the Gnus scores plus the grouplens scores.  To get
the separate scoring behavior you need to set
@code{gnus-grouplens-override-scoring} to @code{'separate}.  To have the
GroupLens predictions combined with the grouplens scores set it to
@code{'override} and to combine the scores set
@code{gnus-grouplens-override-scoring} to @code{'combine}.  When you use
the combine option you will also want to set the values for
@code{grouplens-prediction-offset} and
@code{grouplens-score-scale-factor}.

@vindex grouplens-prediction-display
In either case, GroupLens gives you a few choices for how you would like
to see your predictions displayed.  The display of predictions is
controlled by the @code{grouplens-prediction-display} variable.

The following are legal values for that variable.

@table @code
@item prediction-spot
The higher the prediction, the further to the right an @samp{*} is
displayed. 

@item confidence-interval
A numeric confidence interval.

@item prediction-bar
The higher the prediction, the longer the bar.

@item confidence-bar
Numerical confidence.

@item confidence-spot
The spot gets bigger with more confidence.

@item prediction-num
Plain-old numeric value.

@item confidence-plus-minus
Prediction +/i confidence.

@end table


@node GroupLens Variables
@subsection GroupLens Variables

@table @code

@item gnus-summary-grouplens-line-format
The summary line format used in summary buffers that are GroupLens
enhanced.  It accepts the same specs as the normal summary line format
(@pxref{Summary Buffer Lines}).  The default is
@samp{%U%R%z%l%I%(%[%4L: %-20,20n%]%) %s\n}.

@item grouplens-bbb-host
Host running the bbbd server.  @samp{grouplens.cs.umn.edu} is the
default.

@item grouplens-bbb-port
Port of the host running the bbbd server.  The default is 9000.

@item grouplens-score-offset
Offset the prediction by this value.  In other words, subtract the
prediction value by this number to arrive at the effective score.  The
default is 0.

@item grouplens-score-scale-factor 
This variable allows the user to magnify the effect of GroupLens scores.
The scale factor is applied after the offset.  The default is 1.

@end table


@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 about 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
inverse 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 fules apply to the
grandparent of the current article.  Alternatively, you can write
@code{^^}, where the number of @code{^}s (carets) say 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

Let's say you want to increase the score of articles written by Lars
when he's talking about Gnus:

@example
((& 
  ("from" "Lars Ingebrigtsen")
  ("subject" "Gnus"))
 1000)
@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 Eigir 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

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}, @code{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-score-decay-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.
The decay itself if performed by the @code{gnus-score-decay-function}
function, which is @code{gnus-decay-score} by default.  Here's the
definition of that function:

@lisp
(defun gnus-decay-score (score)
  (floor
   (- score
      (* (if (< score 0) 1 -1)
         (min score
              (max gnus-score-decay-constant
                   (* (abs score)
                      gnus-score-decay-scale)))))))
@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 Various
@chapter Various

@menu
* Process/Prefix::             A convention used by many treatment commands.
* Interactive::                Making Gnus ask you many questions.
* Formatting Variables::       You can specify what buffers should look like.
* Windows Configuration::      Configuring the Gnus buffer windows.
* Compilation::                How to speed Gnus up.
* Mode Lines::                 Displaying information in the mode lines.
* Highlighting and Menus::     Making buffers look all nice and cozy.
* Buttons::                    Get tendonitis in ten easy steps!
* Daemons::                    Gnus can do things behind your back.
* NoCeM::                      How to avoid spam and other fatty foods.
* Picons::                     How to display pictures of what your reading.
* Undo::                       Some actions can be undone.
* Moderation::                 What to do if you're a moderator.
* XEmacs Enhancements::        There are more pictures and stuff under XEmacs.
* Fuzzy Matching::             What's the big fuzz?
* Thwarting Email Spam::       A how-to on avoiding unsolited commercial email.
* 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 that 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 that are 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.


@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 never ever be asked any
questions by Gnus.  It will simply assume you know what you're doing, no
matter how strange.

@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
Require confirmation before exiting Gnus.  This variable is @code{t} by
default. 
@end table


@node Formatting Variables
@section Formatting Variables
@cindex formatting variables

Throughout this manual you've probably noticed lots of variables that
are 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.
* 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.
@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.


@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 legal 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. 
@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.  

If you use lots of these advanced thingies, you'll find that Gnus gets
quite slow.  This can be helped enormously by running @kbd{M-x
gnus-compile} when you are satisfied with the look of your lines.
@xref{Compilation}. 


@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.

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

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.

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[} instead, 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}.

Here's an alternative recipe for the group buffer:

@lisp
;; Create three face types.
(setq gnus-face-1 'bold)
(setq gnus-face-3 'italic)

;; We want the article count to be in 
;; a bold and green face.  So we create 
;; a new face called `my-green-bold'.
(copy-face 'bold 'my-green-bold)
;; Set the color.
(set-face-foreground 'my-green-bold "ForestGreen")
(setq gnus-face-2 'my-green-bold)

;; 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 Windows Configuration
@section Windows Configuration
@cindex windows configuration

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.

@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)
                      (if gnus-carpal (group-carpal 4))))
 (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}. 

Here's a more complicated example:

@lisp
(article (vertical 1.0 (group 4)
                       (summary 0.25 point)
                       (if gnus-carpal (summary-carpal 4))
                       (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.  This means that there will be three buffers if
@code{gnus-carpal} is @code{nil}, and four buffers if @code{gnus-carpal}
is non-@code{nil}.

Not complicated enough for you?  Well, try this on for size:

@lisp
(article (horizontal 1.0 
             (vertical 0.5
                 (group 1.0)
                 (gnus-carpal 4))
             (vertical 1.0
                 (summary 0.25 point)
                 (summary-carpal 4)
                 (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 legal split
may look like:

@example
split       = frame | horizontal | vertical | buffer | form
frame       = "(frame " size *split ")"
horizontal  = "(horizontal " size *split ")"
vertical    = "(vertical " size *split ")"
buffer      = "(" buffer-name " " size *[ "point" ] ")"
size        = number | frame-params
buffer-name = group | article | summary ...
@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)
                   (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}.

Here's a list of all possible keys for
@code{gnus-buffer-configuration}:

@code{group}, @code{summary}, @code{article}, @code{server},
@code{browse}, @code{message}, @code{pick}, @code{info},
@code{summary-faq}, @code{edit-group}, @code{edit-server},
@code{edit-score}, @code{post}, @code{reply}, @code{forward},
@code{reply-yank}, @code{mail-bounce}, @code{draft}, @code{pipe},
@code{bug}, @code{compose-bounce}.

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

@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}.


@node Compilation
@section Compilation
@cindex compilation
@cindex byte-compilation

@findex gnus-compile

Remember all those line format specification variables?
@code{gnus-summary-line-format}, @code{gnus-group-line-format}, and so
on.  Now, Gnus will of course heed whatever these variables are, but,
unfortunately, changing them will mean a quite significant slow-down.
(The default values of these variables have byte-compiled functions
associated with them, while the user-generated versions do not, of
course.) 

To help with this, you can run @kbd{M-x gnus-compile} after you've
fiddled around with the variables and feel that you're (kind of)
satisfied.  This will result in the new specs being byte-compiled, and
you'll get top speed again.  Gnus will save these compiled specs in the
@file{.newsrc.eld} file.  (User-defined functions aren't compiled by
this function, though---you should compile them yourself by sticking
them into the @code{.gnus.el} file and byte-compiling that file.)


@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 Potorti` <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 their
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 prettifying Gnus
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 legal, 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 only highlighting 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 Buttons
@section Buttons
@cindex buttons
@cindex mouse
@cindex click

Those new-fangled @dfn{mouse} contraptions is very popular with the
young, hep kids who don't want to learn the proper way to do things
these days.  Why, I remember way back in the summer of '89, when I was
using Emacs on a Tops 20 system.  Three hundred users on one single
machine, and every user was running Simula compilers.  Bah!

Right.

@vindex gnus-carpal
Well, you can make Gnus display bufferfuls of buttons you can click to
do anything by setting @code{gnus-carpal} to @code{t}.  Pretty simple,
really.  Tell the chiropractor I sent you.


@table @code

@item gnus-carpal-mode-hook
@vindex gnus-carpal-mode-hook
Hook run in all carpal mode buffers.

@item gnus-carpal-button-face
@vindex gnus-carpal-button-face
Face used on buttons.

@item gnus-carpal-header-face
@vindex gnus-carpal-header-face
Face used on carpal buffer headers.

@item gnus-carpal-group-buffer-buttons
@vindex gnus-carpal-group-buffer-buttons
Buttons in the group buffer.

@item gnus-carpal-summary-buffer-buttons
@vindex gnus-carpal-summary-buffer-buttons
Buttons in the summary buffer.

@item gnus-carpal-server-buffer-buttons
@vindex gnus-carpal-server-buffer-buttons
Buttons in the server buffer.

@item gnus-carpal-browse-buffer-buttons
@vindex gnus-carpal-browse-buffer-buttons
Buttons in the browse buffer.
@end table

All the @code{buttons} variables are lists.  The elements in these list
is either a cons cell where the car contains a text to be displayed and
the cdr contains a function symbol, or a simple string.


@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 PGP headers every hour when Emacs is
idle: 

@lisp
(gnus-demon-scan-pgp 60 t)
@end lisp

This @var{time} parameter and than @var{idle} parameter works 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.)

@vindex gnus-use-demon
To set the whole thing in motion, though, you have to set
@code{gnus-use-demon} to @code{t}.

So, if you want to add a handler, you could put something like this in
your @file{.gnus} file:

@findex gnus-demon-add-handler
@lisp
(gnus-demon-add-handler 'gnus-demon-close-connections 30 t)
@end lisp

@findex gnus-demon-add-nocem
@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 has been created:
@code{gnus-demon-add-nocem}, @code{gnus-demon-add-disconnection},
@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} 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 overdo 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 NoCeM
@section NoCeM
@cindex nocem
@cindex spam

@dfn{Spamming} is posting the same article lots and lots of times.
Spamming is bad.  Spamming is evil.  

Spamming is usually canceled within a day or so by various anti-spamming
agencies.  These agencies usually also send out @dfn{NoCeM} messages.
NoCeM is pronounced ``no see-'em'', and means what the name
implies---these are messages that make the offending articles, like, go
away.  

What use are these NoCeM messages if the articles are canceled anyway?
Some sites do not honor cancel messages and some sites just honor cancels
from a select few people.  Then you may wish to make use of the NoCeM
messages, which are distributed in the @samp{alt.nocem.misc} newsgroup.

Gnus can read and parse the messages in this group automatically, and
this will make spam disappear.  

There are some variables to customize, of course:

@table @code
@item gnus-use-nocem
@vindex gnus-use-nocem
Set this variable to @code{t} to set the ball rolling.  It is @code{nil}
by default. 

@item gnus-nocem-groups
@vindex gnus-nocem-groups
Gnus will look for NoCeM messages in the groups in this list.  The
default is @code{("news.lists.filters" "news.admin.net-abuse.bulletins"
"alt.nocem.misc" "news.admin.net-abuse.announce")}. 

@item gnus-nocem-issuers
@vindex gnus-nocem-issuers
There are many people issuing NoCeM messages.  This list says what
people you want to listen to.  The default is @code{("Automoose-1"
"clewis@@ferret.ocunix.on.ca;" "jem@@xpat.com;" "red@@redpoll.mrfs.oh.us
(Richard E. Depew)")}; fine, upstanding citizens all of them.

Known despammers that you can put in this list include:

@table @samp
@item clewis@@ferret.ocunix.on.ca;
@cindex Chris Lewis
Chris Lewis---Major Canadian despammer who has probably canceled more
usenet abuse than anybody else.

@item Automoose-1
@cindex CancelMoose[tm]
The CancelMoose[tm] on autopilot.  The CancelMoose[tm] is reputed to be
Norwegian, and was the person(s) who invented NoCeM.  

@item jem@@xpat.com;
@cindex Jem
John Milburn---despammer located in Korea who is getting very busy these
days.

@item red@@redpoll.mrfs.oh.us (Richard E. Depew)
Richard E. Depew---lone American despammer.  He mostly cancels binary
postings to non-binary groups and removes spews (regurgitated articles).
@end table

You do not have to heed NoCeM messages from all these people---just the
ones you want to listen to.

@item gnus-nocem-verifyer
@vindex gnus-nocem-verifyer
@findex mc-verify
This should be a function for verifying that the NoCeM issuer is who she
says she is.  The default is @code{mc-verify}, which is a Mailcrypt
function.  If this is too slow and you don't care for verification
(which may be dangerous), you can set this variable to @code{nil}.

If you want signed NoCeM messages to be verified and unsigned messages
not to be verified (but used anyway), you could do something like:

@lisp
(setq gnus-nocem-verifyer 'my-gnus-mc-verify)

(defun my-gnus-mc-verify ()
  (not (eq 'forged
           (ignore-errors
             (if (mc-verify)
                 t
               'forged)))))
@end lisp

This might be dangerous, though.

@item gnus-nocem-directory
@vindex gnus-nocem-directory
This is where Gnus will store its NoCeM cache files.  The default is
@file{~/News/NoCeM/}. 

@item gnus-nocem-expiry-wait
@vindex gnus-nocem-expiry-wait
The number of days before removing old NoCeM entries from the cache.
The default is 15.  If you make it shorter Gnus will be faster, but you
might then see old spam.

@end table

Using NoCeM could potentially be a memory hog.  If you have many living
(i. e., subscribed or unsubscribed groups), your Emacs process will grow
big.  If this is a problem, you should kill off all (or most) of your
unsubscribed groups (@pxref{Subscription Commands}).


@node Picons
@section Picons

So...  You want to slow down your news reader even more!  This is a
good way to do so.  Its also a great way to impress people staring
over your shoulder as you read news.

@menu
* Picon Basics::           What are picons and How do I get them.
* Picon Requirements::     Don't go further if you aren't using XEmacs.
* Easy Picons::            Displaying Picons---the easy way.
* Hard Picons::            The way you should do it.  You'll learn something.
* Picon Configuration::    Other variables you can trash/tweak/munge/play with.
@end menu


@node Picon Basics
@subsection Picon Basics

What are Picons?  To quote directly from the Picons Web site:

@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

For instructions on obtaining and installing the picons databases, point
your Web browser at
@file{http://www.cs.indiana.edu/picons/ftp/index.html}.

@vindex gnus-picons-database
Gnus expects picons to be installed into a location pointed to by
@code{gnus-picons-database}.


@node Picon Requirements
@subsection Picon Requirements

To use have Gnus display Picons for you, you must be running XEmacs
19.13 or greater since all other versions of Emacs aren't yet able to
display images.

Additionally, you must have @code{xpm} support compiled into XEmacs.

@vindex gnus-picons-convert-x-face
If you want to display faces from @code{X-Face} headers, you must have
the @code{netpbm} utilities installed, or munge the
@code{gnus-picons-convert-x-face} variable to use something else.


@node Easy Picons
@subsection Easy Picons

To enable displaying picons, simply put the following line in your
@file{~/.gnus} file and start Gnus.

@lisp
(setq gnus-use-picons t)
(add-hook 'gnus-article-display-hook 'gnus-article-display-picons t)
(add-hook 'gnus-summary-prepare-hook 'gnus-group-display-picons t)
(add-hook 'gnus-article-display-hook 'gnus-picons-article-display-x-face)
@end lisp


@node Hard Picons
@subsection Hard Picons 

Gnus can display picons for you as you enter and leave groups and
articles.  It knows how to interact with three sections of the picons
database.  Namely, it can display the picons newsgroup pictures,
author's face picture(s), and the authors domain.  To enable this
feature, you need to first decide where to display them.

@table @code 

@item gnus-picons-display-where 
@vindex gnus-picons-display-where 
Where the picon images should be displayed.  It is @code{picons} by
default (which by default maps to the buffer @samp{*Picons*}).  Other
valid places could be @code{article}, @code{summary}, or
@samp{*scratch*} for all I care.  Just make sure that you've made the
buffer visible using the standard Gnus window configuration
routines---@pxref{Windows Configuration}.

@end table

Note: If you set @code{gnus-use-picons} to @code{t}, it will set up your
window configuration for you to include the @code{picons} buffer.

Now that you've made that decision, you need to add the following
functions to the appropriate hooks so these pictures will get
displayed at the right time.

@vindex gnus-article-display-hook
@vindex gnus-picons-display-where
@table @code
@item gnus-article-display-picons
@findex gnus-article-display-picons
Looks up and display the picons for the author and the author's domain
in the @code{gnus-picons-display-where} buffer.  Should be added to
the @code{gnus-article-display-hook}.

@item gnus-group-display-picons
@findex gnus-article-display-picons
Displays picons representing the current group.  This function should
be added to the @code{gnus-summary-prepare-hook} or to the
@code{gnus-article-display-hook} if @code{gnus-picons-display-where}
is set to @code{article}.

@item gnus-picons-article-display-x-face
@findex gnus-article-display-picons
Decodes and displays the X-Face header if present.  This function
should be added to @code{gnus-article-display-hook}.

@end table

Note:  You must append them to the hook, so make sure to specify 't'
to the append flag of @code{add-hook}:

@lisp
(add-hook 'gnus-article-display-hook 'gnus-article-display-picons t)
@end lisp


@node Picon Configuration
@subsection Picon Configuration

The following variables offer further control over how things are
done, where things are located, and other useless stuff you really
don't need to worry about.

@table @code
@item gnus-picons-database
@vindex gnus-picons-database
The location of the picons database.  Should point to a directory
containing the @file{news}, @file{domains}, @file{users} (and so on)
subdirectories.  Defaults to @file{/usr/local/faces}.

@item gnus-picons-news-directory
@vindex gnus-picons-news-directory
Sub-directory of the faces database containing the icons for
newsgroups.

@item gnus-picons-user-directories
@vindex gnus-picons-user-directories
List of subdirectories to search in @code{gnus-picons-database} for user
faces.  @code{("local" "users" "usenix" "misc/MISC")} is the default.

@item gnus-picons-domain-directories
@vindex gnus-picons-domain-directories
List of subdirectories to search in @code{gnus-picons-database} for
domain name faces.  Defaults to @code{("domains")}.  Some people may
want to add @samp{unknown} to this list.

@item gnus-picons-convert-x-face
@vindex gnus-picons-convert-x-face
The command to use to convert the @code{X-Face} header to an X bitmap
(@code{xbm}).  Defaults to @code{(format "@{ echo '/* Width=48,
Height=48 */'; uncompface; @} | icontopbm | pbmtoxbm > %s"
gnus-picons-x-face-file-name)}

@item gnus-picons-x-face-file-name
@vindex gnus-picons-x-face-file-name
Names a temporary file to store the @code{X-Face} bitmap in.  Defaults
to @code{(format "/tmp/picon-xface.%s.xbm" (user-login-name))}.

@item gnus-picons-buffer
@vindex gnus-picons-buffer
The name of the buffer that @code{picons} points to.  Defaults to
@samp{*Icon Buffer*}.

@end table


@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 that is 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{M-C-_} key performs the @code{gnus-undo} command
command, which should feel kinda like the normal Emacs @code{undo}
command. 


@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 moderation 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 XEmacs Enhancements
@section XEmacs Enhancements
@cindex XEmacs

XEmacs is able to display pictures and stuff, so Gnus has taken
advantage of that.  Relevant variables include:

@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-logo-color-alist
@vindex gnus-xmas-logo-color-alist
This is an alist where the key is a type symbol and the values are the
foreground and background color of the splash page glyph.

@item gnus-xmas-logo-color-style
@vindex gnus-xmas-logo-color-style
This is the key used to look up the color in the alist described above.
Legal values include @code{flame}, @code{pine}, @code{moss},
@code{irish}, @code{sky}, @code{tin}, @code{velvet}, @code{grape},
@code{labia}, @code{berry}, @code{neutral}, and @code{september}.

@item gnus-use-toolbar
@vindex gnus-use-toolbar
If @code{nil}, don't display toolbars.  If non-@code{nil}, it should be
one of @code{default-toolbar}, @code{top-toolbar}, @code{bottom-toolbar},
@code{right-toolbar}, or @code{left-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.

@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


@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 selects the
mail group, only to find two pyramid schemes, seven advertisements
(``New!  Miracle tonic for growing full, lustrouos hair on your toes!'')
and one mail asking me to repent and find some god.

This is annoying.

The way to deal with this is having Gnus split out all spam into a
@samp{spam} mail group (@pxref{Splitting Mail}).

First, pick one (1) legal 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
sysadm 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 @code{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
twarting 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.

If you are also a lazy net citizen, you will probably prefer complaining
automatically with the @file{gnus-junk.el} package, availiable FOR FREE
at @file{<URL:http://stud2.tuwien.ac.at/~e9426626/gnus-junk.html>}.
Since most e-mail spam is sent automatically, this may reconcile the
cosmic balance somewhat.

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-existant domains is yucky, in my opinion.


@node Various Various
@section Various Various
@cindex mode lines
@cindex highlights

@table @code

@item gnus-home-directory
All Gnus path variables will be initialized from this variable, which
defaults to @file{~/}.

@item gnus-directory
@vindex gnus-directory
Most Gnus storage path variables will be initialized from this variable,
which defaults to the @samp{SAVEDIR} environment variable, or
@file{~/News/} if that variable isn't set.

@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 backends instead of Gnus proper.

@item nnheader-max-head-length
@vindex nnheader-max-head-length
When the backends read straight heads of articles, they all try to read
as little as possible.  This variable (default 4096) specifies
the absolute max length the backends 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 backends 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}. 

@item nnheader-head-chop-length
@vindex nnheader-head-chop-length
This variable 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 illegal 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 illegal as a file character in file names
on your system (you OS/2 user you), you could say something like:

@lisp
(setq nnheader-file-name-translation-alist 
      '((?: . ?_)))
@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 to shell commands.  The default is @samp{;}. 


@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
* History::                        How Gnus got where it is today.
* Terminology::                    We use really difficult, like, words here.
* Customization::                  Tailoring Gnus to your needs.
* Troubleshooting::                What you might try if things do not work.
* A Programmers Guide to Gnus::    Rilly, rilly technical stuff.
* Emacs for Heathens::             A short introduction to Emacsian terms.
* Frequently Asked Questions::     A question-and-answer session.
@end menu


@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
@file{http://www.ifi.uio.no/~larsi/}.  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.

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''.

If you happen upon a version of Gnus that has a name that is prefixed --
``(ding) Gnus'', ``September Gnus'', ``Red Gnus'', ``Quassia 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.

@menu
* 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.
* Contributors::        Oodles of people.  
* New Features::        Pointers to some of the new stuff in Gnus.
* Newest Features::     Features so new that they haven't been written yet.
@end menu


@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 backends, Gnus now offers a simple
interface for anybody who wants to write new backends for fetching mail
and news from different sources.  I have added hooks for customizations
everywhere I could imagine 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 hail-emacs}. 


@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. @pxref{Decoding
Articles}. 

One major compatibility question is the presence of several summary
buffers.  All variables that are 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}.


@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 822
@cindex RFC 822
There are no known breaches of this standard.

@item RFC 1036
@cindex RFC 1036
There are no known breaches of this standard, either.

@item Good Net-Keeping Seal of Approval
@cindex Good Net-Keeping Seal of Approval
Gnus has been through the Seal process and failed.  I think it'll pass
the next inspection.

@item Son-of-RFC 1036
@cindex Son-of-RFC 1036
We do have some breaches to this one.

@table @emph

@item MIME
Gnus does no MIME handling, and this standard-to-be seems to think that
MIME is the bees' knees, so we have major breakage here.

@item X-Newsreader
This is considered to be a ``vanity header'', while I consider it 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

@end table

If you ever notice Gnus acting non-compliantly 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

Gnus should work on :

@itemize @bullet 

@item
Emacs 19.32 and up.

@item
XEmacs 19.14 and up.

@item 
Mule versions based on Emacs 19.32 and up.

@end itemize

Gnus will absolutely not work on any Emacsen older than that.  Not
reliably, at least. 

There are some vague differences between Gnus on the various
platforms---XEmacs features more graphics (a logo and a toolbar)---but
other than that, things should look pretty much the same under all
Emacsen. 


@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...  oops,
wrong show.

@itemize @bullet

@item 
Masanobu @sc{Umeda}---the writer of the original @sc{gnus}.

@item 
Per Abrahamsen---custom, scoring, highlighting and @sc{soup} code (as
well as numerous other things).

@item 
Luis Fernandes---design and graphics.

@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
(@pxref{GroupLens}).

@item 
Sudish Joseph---innumerable bug fixes.

@item 
Ilja Weis---@file{gnus-topic.el}.

@item 
Steven L. Baur---lots and lots and lots of bugs detections and fixes.

@item 
Vladimir Alexiev---the refcard and reference booklets.

@item 
Felix Lee & Jamie Zawinsky---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 
Ricardo Nassif, Mark Borges, and Jost Krieger---proof-reading.

@item 
Kevin Davidson---came up with the name @dfn{ding}, so blame him.

@item
François Pinard---many, many interesting and thorough bug reports.

@end itemize

The following people have contributed many patches and suggestions: 

Christopher Davis,
Andrew Eskilsson,
Kai Grossjohann,
David Kågedal,
Richard Pieri,
Fabrice Popineau, 
Daniel Quinlan, 
Jason L. Tibbitts, III,
and
Jack Vinson.

Also thanks to the following for patches and stuff:

Adrian Aichner,
Peter Arius, 
Matt Armstrong,
Marc Auslander,
Chris Bone,
Mark Borges,
Lance A. Brown,
Kees de Bruin,
Martin Buchholz,
Kevin Buhr,
Alastair Burt,
Joao Cachopo,
Zlatko Calusic,
Massimo Campostrini,
Michael R. Cook,
Glenn Coombs, 
Frank D. Cringle, 
Geoffrey T. Dairiki,
Andre Deparade,
Ulrik Dickow,
Dave Disser,
Joev Dubach,
Michael Welsh Duggan,
Paul Eggert,
Michael Ernst,
Luc Van Eycken,
Sam Falkner,
Paul Franklin, 
Arne Georg Gleditsch,
David S. Goldberg,
D. Hall, 
Magnus Hammerin,
Raja R. Harinath,
Hisashige Kenji, @c Hisashige
Marc Horowitz,
Gunnar Horrigmo,
Brad Howes,
François Felix Ingrand,
Ishikawa Ichiro, @c Ishikawa
Lee Iverson, 
Rajappa Iyer,
Randell Jesup,
Fred Johansen, 
Greg Klanderman,
Karl Kleinpaste,
Peter Skov Knudsen,
Shuhei Kobayashi, @c Kobayashi
Thor Kristoffersen,
Jens Lautenbacher,
Carsten Leonhardt,
James LewisMoss,
Christian Limpach,
Markus Linnala,
Dave Love,
Tonny Madsen,
Shlomo Mahlab,
Nat Makarevitch,
David Martin,
Gordon Matzigkeit,
Timo Metzemakers,
Richard Mlynarik,
Lantz Moore,
Morioka Tomohiko, @c Morioka
Erik Toubro Nielsen,
Hrvoje Niksic,
Andy Norman,
C. R. Oldham,
Alexandre Oliva,
Ken Olstad,
Masaharu Onishi, @c Onishi
Hideki Ono, @c Ono
William Perry,
Stephen Peters,
Ulrich Pfeifer,
John McClary Prevost,
Colin Rafferty,
Bart Robinson,
Jason Rumney,
Dewey M. Sasser,
Loren Schall,
Dan Schmidt,
Ralph Schleicher,
Philippe Schnoebelen,
Randal L. Schwartz,
Danny Siu, 
Paul D. Smith,
Jeff Sparkes,
Toby Speight,
Michael Sperber,
Richard Stallman,
Greg Stark, 
Paul Stodghill,
Kurt Swanson,
Samuel Tardieu, 
Teddy,
Chuck Thompson,
Philippe Troin,
Aaron M. Ucko,
Jan Vroonhof,
Barry A. Warsaw,
Christoph Wedler,
Joe Wells,
and
Katsumi Yamaoka. @c Yamaoka

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 5.3/5.3.
* Red Gnus::           Third time best---Gnus 5.4/5.5.
@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 @sc{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 backends 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}) 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 grep through a subset of groups and create a group from the
results (@pxref{Kibozed Groups}). 

@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 FAQs 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{Windows Configuration}).

@item
You can click on buttons instead of using the keyboard
(@pxref{Buttons}). 

@end itemize


@node September Gnus
@subsubsection September Gnus

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 (@pxref{GroupLens}).

@item
Picons (personal icons) can be displayed under XEmacs (@pxref{Picons}). 

@item
A @code{trn}-line 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 backend (@code{nnsoup}) to create/read SOUP packets
(@pxref{SOUP}).

@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-address 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}).

@lisp
(add-hook 'gnus-article-display-hook 
          'gnus-article-add-buttons-to-head)
@end lisp

@item
All mail backends 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{Windows
Configuration}).

@item
Mail can be re-scanned by a daemonic process (@pxref{Daemons}).

@item
Gnus can make use of NoCeM files to weed out spam (@pxref{NoCeM}).

@lisp
(setq gnus-use-nocem t)
@end lisp

@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}).

@lisp
(add-hook 'gnus-article-display-hook 
          'gnus-article-hide-boring-headers t)
@end lisp

@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:

@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}).

@item
@code{nndoc} was rewritten to be easily extendable (@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
A way 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{M-C-_}
(@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{M-C-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 backend makes it possible to post even when the NNTP
server doesn't allow posting (@pxref{Mail-To-News Gateways}).

@item
A new backend 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}).
  
@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:

@lisp
(add-hook 'gnus-article-display-hook 'gnus-article-emphasize)
@end lisp
 
@end itemize


@node Newest Features
@subsection Newest Features
@cindex todo

Also known as the @dfn{todo list}.  Sure to be implemented before the
next millennium. 

Be afraid.  Be very afraid.

@itemize @bullet
@item
Native @sc{mime} support is something that should be done.  
@item
Really do unbinhexing.
@end itemize

And much, much, much more.  There is more to come than has already been
implemented.  (But that's always true, isn't it?)

@file{<URL:http://www.ifi.uio.no/~larsi/rgnus/todo>} is where the actual
up-to-the-second todo list is located, so if you're really curious, you
could point your Web browser over that-a-way.

@iftex

@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 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 @sc{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 backend
@cindex backend
Gnus gets fed articles from a number of backends, both news and mail
backends.  Gnus does not handle the underlying media, so to speak---this
is all done by the backends.

@item native
@cindex native
Gnus will always use one method (and backend) as the @dfn{native}, or
default, way of getting news.

@item foreign
@cindex foreign
You can also have any number of foreign groups active at the same time.
These are groups that use different backends for getting news.

@item secondary
@cindex secondary
Secondary backends are somewhere half-way between being native and being
foreign, but they mostly act like they are native.

@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 that is 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 @sc{nov} lines.

@item @sc{nov}
@cindex nov
When Gnus enters a group, it asks the backend 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.

@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 server 
@cindex server
A machine than one can connect to and get news (or mail) from.

@item select method
@cindex select method
A structure that specifies the backend, the server and the virtual
server parameters.

@item virtual server
@cindex virtual server
A named select method.  Since a select methods defines all there is to
know about connecting to a (physical) server, taking the things 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
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.

@end table


@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 @sc{nntp} 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 @sc{nntp} 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 v.  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
This one has to be @code{nil}.  If not, grabbing article headers from
the @sc{nntp} server will not be very fast.  Not all @sc{nntp} servers
support @sc{xover}; Gnus will detect this by itself.
@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 the
amount of data that is sent over the wires as much as possible.

@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 that are 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.

@item gnus-article-display-hook
Set this hook to all the available hiding commands:
@lisp
(setq gnus-article-display-hook 
      '(gnus-article-hide-headers gnus-article-hide-signature
        gnus-article-hide-citation))
@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-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.

Set @code{gnus-article-display-hook} to @code{nil} to make article
processing a bit faster.


@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 @samp{Gnus v5.46; nntp 4.0} you have the right files loaded.  If,
on the other hand, you get something like @samp{NNTP 3.x} or @samp{nntp
flee}, 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 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 send back
just ``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.

If you just need help, you are better off asking on
@samp{gnu.emacs.gnus}.  I'm not very helpful.

@cindex gnu.emacs.gnus
@cindex ding mailing list
You can also ask on the ding mailing list---@samp{ding@@gnus.org}.
Write to @samp{ding-request@@gnus.org} to subscribe.


@node A Programmers Guide to Gnus
@section A Programmer@'s Guide to Gnus

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
backends (this is written in stone), the format of the score files
(ditto), data structures (some are less likely to change than others)
and general method of operations.

@menu 
* Gnus Utility Functions::   Common functions and variable to use.
* Backend 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.
* 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
Return the group info list for @var{group}.

@item gnus-add-current-to-buffer-list
@findex gnus-add-current-to-buffer-list
Add the current buffer to the list of buffers to be killed on Gnus
exit.

@item gnus-continuum-version
@findex gnus-continuum-version
Take 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
Say whether @var{group} is read-only or not.

@item gnus-news-group-p
@findex gnus-news-group-p
Say whether @var{group} came from a news backend.

@item gnus-ephemeral-group-p
@findex gnus-ephemeral-group-p
Say whether @var{group} is ephemeral or not.

@item gnus-server-to-method
@findex gnus-server-to-method
Return the select method corresponding to @var{server}.

@item gnus-server-equal
@findex gnus-server-equal
Say whether two virtual servers are equal.

@item gnus-group-native-p
@findex gnus-group-native-p
Say whether @var{group} is native or not.

@item gnus-group-secondary-p
@findex gnus-group-secondary-p
Say whether @var{group} is secondary or not.

@item gnus-group-foreign-p
@findex gnus-group-foreign-p
Say whether @var{group} is foreign or not.

@item group-group-find-parameter
@findex group-group-find-parameter
Return the parameter list of @var{group}.  If given a second parameter,
return 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
Narrow 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 backend
@var{group} comes from supports @var{function}, return non-@code{nil}.

@lisp
(gnus-check-backend-function "request-scan" "nnml:misc")
=> t
@end lisp

@item gnus-read-method
@findex gnus-read-method
Prompt the user for a select method.

@end table


@node Backend Interface
@subsection Backend Interface

Gnus doesn't know anything about @sc{nntp}, spools, mail or virtual
groups.  It only knows how to talk to @dfn{virtual servers}.  A virtual
server is a @dfn{backend} and some @dfn{backend 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 backend---say @code{nntp}---on
something, it will normally include a virtual server name in the
function parameters.  (If not, the backend 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 backends should be able to switch between several virtual servers.
The standard backends implement this by keeping an alist of virtual
server environments that it pulls down/pushes 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 whether are present before attempting to call.

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 backends could be said to be @dfn{server-forming} backends, and
some might be said to not be.  The latter are backends 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.

In the examples and definitions I will refer to the imaginary backend
@code{nnchoke}. 

@cindex @code{nnchoke}

@menu
* Required Backend Functions::        Functions that must be implemented.
* Optional Backend Functions::        Functions that need not be implemented.
* Error Messaging::                   How to get messages and report errors.
* Writing New Backends::              Extending old backends.
* Hooking New Backends Into Gnus::    What has to be done on the Gnus end.
* Mail-like Backends::                Some tips on mail backends.
@end menu


@node Required Backend Functions
@subsubsection Required Backend 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 backends do not fully support either---only
sequences (lists) of article numbers, and most backends do not support
retrieval of @code{Message-ID}s.  But they should try for both. 

The result data should either be HEADs or 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 NOV lines, but this is currently not supported by Gnus.  

If @var{fetch-old} is non-@code{nil} it says to try to fetch "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 fill in the gaps as well.  The
presence of this parameter can be ignored if the backend 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

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   = 8*9 [ field <TAB> ] eol
field      = <text except TAB>
@end example

For a closer explanation 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 defines this virtual server. 

If the server can't be opened, no error should be signaled.  The backend
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 backend
have reserved.  All buffers that have been created by that backend
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} vlue.  This function should under no circumstances
attempt to reconnect to a server that is has 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, and Gnus mainly request articles to be inserted directly into
its article buffer.

If it is at all possible, this function should return a cons cell where
the car is the group name the article was fetched from, and the 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 retrievement.


@item (nnchoke-request-group GROUP &optional SERVER FAST)

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.

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.

@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 backends. 

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.

@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 Backend Functions
@subsubsection Optional Backend 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 backend for
alterations.  This comes in handy if the backend 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 the (altered) group info.

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 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-update-mark GROUP ARTICLE MARK)

If the user tries to set a mark that the backend 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 backend 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 that 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 backend check for incoming articles, in one way or
another.  A mail backend will typically read the spool file or query the
POP server when this function is invoked.  The @var{group} doesn't have
to be heeded---if the backend 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.  The data should be in the active buffer format.


@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 backend 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 car is the group name and
the 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 car is the group name and
the cdr is the article number that the article was entered as.

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 that are 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 backends 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 backend
symbol, and the rest are interpreted as arguments to @code{format} if
there are many of them, or just a string if there is one of them.
This function 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 backend in question.  This function
takes one argument---the server symbol.

Internally, these function access @var{backend}@code{-status-string}, so
the @code{nnchoke} backend will have its error message stored in
@code{nnchoke-status-string}. 


@node Writing New Backends
@subsubsection Writing New Backends

Many backends 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
backends when writing new backends.  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 backends declare their public variables and functions by using a
package called @code{nnoo}.  

To inherit functions from other backends (and allow other backends to
inherit functions from the current backend), you should use the
following macros:
following. 

@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 here declared 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 backends to map the variable to when executing
a function in those backends.

@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 backends should
have.

@example
(nnoo-define-basics nndir)
@end example

@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 backends can inherit it.

@item nnoo-map-functions
This macro allows mapping of functions from the current backend to
functions from the parent backends.

@example
(nnoo-map-functions nndir
  (nnml-retrieve-headers 0 nndir-current-group 0 0)
  (nnmh-request-article 0 nndir-current-group 0 0))
@end example

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 backends.  It should be the
last thing in the source file, since it will only define functions that
haven't already been defined.

@example
(nnoo-import nndir
  (nnmh
   nnmh-request-list
   nnmh-request-newgroups)
  (nnml))
@end example

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} backend.

@lisp
;;; nndir.el --- single directory newsgroup access for Gnus
;; Copyright (C) 1995,96 Free Software Foundation, Inc.

;;; 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")

;;; 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 Backends Into Gnus
@subsubsection Hooking New Backends Into Gnus

@vindex gnus-valid-select-methods
Having Gnus start using your new backend is rather easy---you just
declare it with the @code{gnus-declare-backend} functions.  This will
enter the backend into the @code{gnus-valid-select-methods} variable.

@code{gnus-declare-backend} takes two parameters---the backend name and
an arbitrary number of @dfn{abilities}.

Here's an example:

@lisp
(gnus-declare-backend "nnchoke" 'mail 'respool 'address)
@end lisp

The abilities can be:

@table @code
@item mail
This is a mailish backend---followups should (probably) go via mail.
@item post
This is a newsish backend---followups should (probably) go via news. 
@item post-mail
This backend supports both mail and news.
@item none
This is neither a post or mail backend---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 backends.
@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 backends like
@code{nntp}, but not @code{nnmbox}, for instance. 
@end table


@node Mail-like Backends
@subsubsection Mail-like Backends

One of the things that separate the mail backends from the rest of the
backends is the heavy dependence by the mail backends 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 just calls @code{nnmail-get-new-mail} will 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 backend 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{backend}@code{-save-mail} to
save each article.  @var{backend}@code{-active-number} will be called to
find the article number assigned to this article.  

The function also uses the following variables:
@var{backend}@code{-get-new-mail} (to see whether to get new mail for
this backend); and @var{backend}@code{-group-alist} and
@var{backend}@code{-active-file} to generate the new active file.
@var{backend}@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
mallable.   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"
  ("win95" -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. 


@node Headers
@subsection Headers

Gnus uses internally a format for storing article headers that
corresponds to the @sc{nov} format in a mysterious fashion.  One could
almost suspect that the author looked at the @sc{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
RFC1036 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}.  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.

The @code{xref} slot is really a @code{misc} slot.  Any extra info will
be put in there.


@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 legal:

@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 (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.  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 level space read 
                [ "" / [ space marks-list [ "" / [ space method [ "" /
                space parameters ] ] ] ] ] ")" 
group         = quote <string> quote
level         = <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.

@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.

@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 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 when 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 that are 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 space high-number space low-number space flag <NEWLINE>
group       = <non-white-space string>
space       = " "
high-number = <non-negative integer>
low-number  = <positive integer>
flag        = "y" / "n" / "m" / "j" / "x" / "=" group
@end example


@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


@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{M-C-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 key is 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
keyboards.  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 doesn't say ``press the meta-control-m key'',
because that's just too inconvenient.  We say ``press the @kbd{M-C-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{M-C-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{.emacs} file
to customize Gnus.

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 @code{.emacs} file with lots of these to change
how Gnus works.

If you have put that thing in your @code{.emacs} file, it will be read
and @code{eval}ed (which is lisp-ese for ``run'') the next time you
start Emacs.  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 here is a simple @code{setq} statement.

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} to
@samp{nntp.ifi.uio.no}'', that means:

@lisp
(setq gnus-nntp-server "nntp.ifi.uio.no")
@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.


@include gnus-faq.texi

@node Index
@chapter Index
@printindex cp

@node Key Index
@chapter Key Index
@printindex ky

@summarycontents
@contents
@bye

@iftex
@iflatex
\end{document}
@end iflatex
@end iftex

@c End: