Rewrite the introduction about version systems, mentioning the new

ones that we support.  Thanks to Alex Ott, Karl Fogel, Stefan
Monnier, and David Kastrup for suggestions.

diff --git a/man/files.texi b/man/files.texi
index 4e36c2ab2fafc0c20df4520f9753e2e02261d252..6a0d2c662b508ae96c82fffc2480b0d28e54b896 100644 (file)
--- a/man/files.texi
+++ b/man/files.texi
@@ -1119,11 +1119,13 @@ such as the creation time of each version, who created it, and a
 description of what was changed in that version.
 
   The Emacs version control interface is called VC.  Its commands work
 description of what was changed in that version.
 
   The Emacs version control interface is called VC.  Its commands work

-with three version control systems---RCS, CVS, and SCCS.  The GNU
-project recommends RCS and CVS, which are free software and available
-from the Free Software Foundation.  We also have free software to
-replace SCCS, known as CSSC; if you are using SCCS and don't want to
-make the incompatible change to RCS or CVS, you can switch to CSSC.
+with different version control systems---currently, it supports CVS,
+GNU Arch, RCS, Meta-CVS, Subversion, and SCCS.  Of these, the GNU
+project distributes CVS, GNU Arch, and RCS; we recommend that you use
+either CVS or GNU Arch for your projects, and RCS for individual
+files.  We also have free software to replace SCCS, known as CSSC; if
+you are using SCCS and don't want to make the incompatible change to
+RCS or CVS, you can switch to CSSC.

 
   VC is enabled by default in Emacs.  To disable it, set the
 customizable variable @code{vc-handled-backends} to @code{nil}
 
   VC is enabled by default in Emacs.  To disable it, set the
 customizable variable @code{vc-handled-backends} to @code{nil}


@@ -1164,31 +1166,61 @@ you want to use.
 @node Version Systems
 @subsubsection Supported Version Control Systems
 
 @node Version Systems
 @subsubsection Supported Version Control Systems
 

-@cindex RCS

 @cindex back end (version control)
 @cindex back end (version control)

-  VC currently works with three different version control systems or
-``back ends'': RCS, CVS, and SCCS.
-
-  RCS is a free version control system that is available from the Free
-Software Foundation.  It is perhaps the most mature of the supported
-back ends, and the VC commands are conceptually closest to RCS.  Almost
-everything you can do with RCS can be done through VC.
+  VC currently works with six different version control systems or
+``back ends'': CVS, GNU Arch, RCS, Meta-CVS, Subversion, and SCCS.

 
 @cindex CVS
 
 @cindex CVS

-  CVS is built on top of RCS, and extends the features of RCS, allowing
-for more sophisticated release management, and concurrent multi-user
-development.  VC supports basic editing operations under CVS, but for
-some less common tasks you still need to call CVS from the command line.
-Note also that before using CVS you must set up a repository, which is a
-subject too complex to treat here.
+  CVS is a free version control system that is used for the majority
+of free software projects today.  It allows concurrent multi-user
+development either locally or over the network.  Some of its
+shortcomings, corrected by newer systems such as GNU Arch, are that it
+lacks atomic commits or support for renaming files.  VC supports all
+basic editing operations under CVS, but for some less common tasks you
+still need to call CVS from the command line.  Note also that before
+using CVS you must set up a repository, which is a subject too complex
+to treat here.
+
+@cindex GNU Arch
+@cindex Arch
+  GNU Arch is a new version control system that is designed for
+distributed work.  It differs in many ways from old well-known
+systems, such as CVS and RCS.  It supports different transports for
+interoperating between users, offline operations, and it has good
+branching and merging features.  It also supports atomic commits, and
+history of file renaming and moving.  VC does not support all
+operations provided by GNU Arch, so you must sometimes invoke it from
+the command line, or use a specialized module.
+
+@cindex RCS
+  RCS is the free version control system around which VC was initially
+built.  The VC commands are therefore conceptually closest to RCS.
+Almost everything you can do with RCS can be done through VC.  You
+cannot use RCS over the network though, and it only works at the level
+of individual files, rather than projects.  You should use it if you
+want a simple, yet reliable tool for handling individual files.
+
+@cindex SVN
+@cindex Subversion
+  Subversion is a free version control system designed to be similar
+to CVS but without CVS's problems.  Subversion supports atomic commits,
+and versions directories, symbolic links, meta-data, renames, copies,
+and deletes.  It can be used via http or via its own protocol.
+
+@cindex MCVS
+@cindex Meta-CVS
+  Meta-CVS is another attempt to solve problems, arising in CVS.  It
+supports directory structure versioning, improved branching and
+merging, and use of symbolic links and meta-data in repositories.

 
 @cindex SCCS
   SCCS is a proprietary but widely used version control system.  In
 
 @cindex SCCS
   SCCS is a proprietary but widely used version control system.  In

-terms of capabilities, it is the weakest of the three that VC
-supports.  VC compensates for certain features missing in SCCS
-(snapshots, for example) by implementing them itself, but some other VC
-features, such as multiple branches, are not available with SCCS.  You
-should use SCCS only if for some reason you cannot use RCS.
+terms of capabilities, it is the weakest of the six that VC supports.
+VC compensates for certain features missing in SCCS (snapshots, for
+example) by implementing them itself, but some other VC features, such
+as multiple branches, are not available with SCCS.  You should use
+SCCS only if for some reason you cannot use RCS, or one of the
+higher-level systems such as CVS or GNU Arch.

 
 @node VC Concepts
 @subsubsection Concepts of Version Control
 
 @node VC Concepts
 @subsubsection Concepts of Version Control