** Gnus changes.

Gnus, the Emacs newsreader, has undergone further rewriting.  Many new
commands and variables have been added.  There should be no
significant incompatibilities between this Gnus version and the
previously released version, except in the message composition area.

Below is a list of the more user-visible changes.  Coding changes
between Gnus 5.1 and 5.2 are more extensive.

*** A new message composition mode is used.  All old customization 
variables for mail-mode, rnews-reply-mode and gnus-msg are now
obsolete.

*** Gnus is now able to generate "sparse" threads -- threads where
missing articles are represented by empty nodes.

    (setq gnus-build-sparse-threads 'some)

*** Outgoing articles are stored on a special archive server.

    To disable this:  (setq gnus-message-archive-group nil)

*** Partial thread regeneration now happens when articles are
referred. 

*** Gnus can make use of GroupLens predictions:

    (setq gnus-use-grouplens t)

*** Picons (personal icons) can be displayed under XEmacs.

    (setq gnus-use-picons t)

*** A trn-line tree buffer can be displayed.

    (setq gnus-use-trees t)

*** An nn-like pick-and-read minor mode is available for the summary
buffers. 

    (add-hook 'gnus-summary-mode-hook 'gnus-pick-mode)

*** In binary groups you can use a special binary minor mode:

    `M-x gnus-binary-mode'

*** Groups can be grouped in a folding topic hierarchy.

    (add-hook 'gnus-group-mode-hook 'gnus-topic-mode)

*** Gnus can re-send and bounce mail.

    Use the `S D r' and `S D b'.

*** Groups can now have a score, and bubbling based on entry frequency
is possible.

    (add-hook 'gnus-summary-exit-hook 'gnus-summary-bubble-group)

*** Groups can be process-marked, and commands can be performed on
groups of groups.

*** Caching is possible in virtual groups.

*** nndoc now understands all kinds of digests, mail boxes, rnews news
batches, ClariNet briefs collections, and just about everything else. 

*** Gnus has a new backend (nnsoup) to create/read SOUP packets.

*** The Gnus cache is much faster.

*** Groups can be sorted according to many criteria.

    For instance: (setq gnus-group-sort-function 'gnus-group-sort-by-rank)

*** New group parameters have been introduced to set list-address and
expiry times.

*** All formatting specs allow specifying faces to be used.

*** There are several more commands for setting/removing/acting on
process marked articles on the `M P' submap.

*** 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 `/' submap.

*** Articles can be made persistent -- as an alternative to saving
articles with the `*' command.

*** All functions for hiding article elements are now toggles.

*** Article headers can be buttonized.

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

*** All mail backends support fetching articles by Message-ID.

*** Duplicate mail can now be treated properly.  See the 
`nnmail-treat-duplicates' variable.

*** All summary mode commands are available directly from the article
buffer. 

*** Frames can be part of `gnus-buffer-configuration'.

*** Mail can be re-scanned by a daemonic process.

*** Gnus can make use of NoCeM files to filter spam.

    (setq gnus-use-nocem t)

*** Groups can be made permanently visible. 

    (setq gnus-permanently-visible-groups "^nnml:")

*** Many new hooks have been introduced to make customizing easier. 

*** Gnus respects the Mail-Copies-To header.

*** Threads can be gathered by looking at the References header. 

    (setq gnus-summary-thread-gathering-function 
          'gnus-gather-threads-by-references)

*** Read articles can be stored in a special backlog buffer to avoid
refetching.  

    (setq gnus-keep-backlog 50)

*** A clean copy of the current article is always stored in a separate
buffer to allow easier treatment.

*** Gnus can suggest where to save articles.  See `gnus-split-methods'.

*** Gnus doesn't have to do as much prompting when saving.

    (setq gnus-prompt-before-saving t)

*** gnus-uu can view decoded files asynchronously while fetching
articles. 

    (setq gnus-uu-grabbed-file-functions 'gnus-uu-grab-view)

*** Filling in the article buffer now works properly on cited text. 

*** Hiding cited text adds buttons to toggle hiding, and how much
cited text to hide is now customizable.

    (setq gnus-cited-lines-visible 2)

*** Boring headers can be hidden.

    (add-hook 'gnus-article-display-hook 'gnus-article-hide-boring-headers)

*** Default scoring values can now be set from the menu bar.

*** Further syntax checking of outgoing articles have been added.

The Gnus manual has been expanded.  It explains all these new features
in greater detail.