                 X.Org and XFree86 Version Numbering Schemes

                          The XFree86 Project, Inc
          Updated for X11R6.9 by Keith Packard and Kevin E. Martin

                              21 December 2005

                                  Abstract

     X.Org has adopted the same basic numbering scheme used by the
     XFree86 Project, Inc. for their releases.  The actual numbers are
     different, but the basic scheme is the same.  This document
     reflects the policy that X.Org uses.  The version numbering schemes
     used by XFree86 have changed from time to time.

1.  Releases, Development Streams and Branches

As of the release of version X11R6.7 in March 2004, X.Org has three release
branches.  First is the trunk of the CVS repository.  This is the main devel-
opment stream, where all new work and work for future releases is done.

Second is the stable bugfix branch for the latest full release (6.9.0).  It
is created around the time of the release.  The branch for the current
release is called "XORG-6_9-branch".  Fixes for bugs found in the release
will be added to this branch (as well as the trunk), and updates to this
release (if any) will be cut from this branch.  Similar stable branches are
present for previous full releases.

The X.Org Foundation is planning to make full releases from the main develop-
ment stream at regular intervals in the 6-12 month range.  The feature
freezes for these releases will usually be 2-3 months before the release
dates.  This general plan is a goal, not a binding commitment.  The actual
release intervals and dates will depend to a large degree on the resource
available to X.Org.  Full releases consist of full source code tarballs, plus
full binary distributions for a range of supported platforms.  Update/bugfix
releases will be made on an as-required basis, depending also on the avail-
ability of resources, and will generally be limited to serious bug and secu-
rity fixes.  New features will not usually be added in update releases.
Update/bugfix releases will not be full releases, and will consist of source
code patches, plus binary updates to be layered on top of the previous full
release.

The next full release will be version 7.1.  There is no scheduled update
release, but if one is needed, the version will be 6.9.1.

Aside from actual releases, snapshots of the active release branches are
tagged in the CVS repository from time to time.  Each such snapshot has an
identifiable version number.

2.  Current (new) Version Numbering Scheme

Starting with the main development branch after X11R6.7, the X.Org versions
are numbered according to the scheme outlined here.

The version numbering format is M.m.P.s, where M is the major version number,
m is the minor version number, P is the patch level, and s is the snapshot
number.  Full releases have P set to zero, and it is incremented for each
subsequent bug fix release on the post-release stable branch.  The snapshot
number s is present only for between-release snapshots of the development and
stable branches.

2.1  Development Branch

Immediately after forming a release stable branch, the patch level number for
the main development branch is bumped to 99, and the snapshot number is
reset.  The snapshot number is incremented for each tagged development snap-
shot.  The CVS tag for snapshots is "XORG-M_m_P_s".  When the development
branch enters feature freeze, the snapshot number is bumped to 900.  A stable
branch may be created for the next full release at any time after the feature
freeze.  When it is, the branch is called "XORG-M_m-branch".  The snapshot
number is incremented from there until the release is finalised.  Each of
these snapshots is a "release candidate".  When the release is finalised, the
minor version is incremented, the patch level is set to zero, and the snap-
shot number removed.

Here's an example which shows the version number sequence for the development
leading up to version 6.8:

      6.7.99.1
            The first snapshot of the pre-6.8 development branch.

      6.7.99.23
            The twenty-third snapshot of the pre-6.8 development branch.

      6.7.99.900
            The start of the 6.8 feature freeze.

      6.7.99.903
            The third 6.8 release candidate.

      6.8.0
            The 6.8 release.

      6.8.99.1
            The first pre-6.9 development snapshot, which  is the first main
            branch snapshot after creating the 6.8 stable branch.

2.2  Stable Branch

After a full release, the stable branch for the release will be maintained
with bug fixes and important updates until the next full release.  Any snap-
shots on this branch are considered "release candidates", which is indicated
by setting s to a number above 900.  The snapshot number is incremented for
each release candidate until the update release is finalised.  The patch
level value (P) is incremented for each update release.

Here's an example which shows a version number sequence for a 6.8.x stable
branch:

      6.8.0
            The 6.8 release.

      6.8.0.901
            The first pre 6.8.1 snapshot.

      6.8.0.903
            The third pre 6.8.1 snapshot, also known as the third 6.8.1
            release candidate.

      6.8.1
            The 6.8.1 release.

      6.8.1.901
            The first pre 6.8.2 snapshot.

      6.8.2
            The 6.8.2 release.

3.  Finding the X.Org X Server Version From a Client

The X.Org X servers report a VendorRelease value that matches the X.Org ver-
sion number.  There have been some cases of releases where this value wasn't
set correctly.  The rules for interpreting this value as well as the known
exceptions are outlined here.

For post-6.7.0 development and release versions using the new numbering
scheme, the VendorRelease value is MMmmPPsss.  That is, version M.m.P.s has
VendorRelease set to M * 10000000 + m * 100000 + P * 1000 + s.

The following is a code fragment taken from xdpyinfo.c that shows how the
VendorRelease information can be interpreted.

         if (strstr(ServerVendor(dpy), "X.Org")) {
             int vendrel = VendorRelease(dpy);

             printf("X.Org version: ");
          printf("%d.%d.%d", vendrel / 10000000,
                 (vendrel /   100000) % 100,
                 (vendrel /     1000) % 100);
          if (vendrel % 1000) {
              printf(".%d", vendrel % 1000);
          }
         }


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