Starting with the X11R7.0 release, each module has its own version number. For those without a natural starting point, the version numbers started at 1.0. For instance, the X11R7.0 release included the xorg-server 1.0 module. As modules are released independently from the rest of the window system, the module version is the most accurate source of version information. For instance, there are many X server releases in a year, but generally only one window system release, so an X server version number such as 1.7.7 is more informative than the X11R7.5 version for the window system “katamari” release.

Unfortunately, up through the X server 1.3 release, the X server used the Window System version when reporting its version number in log files, the -version option, and the connection setup string (displayed by xdpyinfo). This was corrected with X server 1.3, which caused the visible version number string to appear to jump backwards from 7.2 to 1.3.

X.Org has two release branches for the X server software, and several other modules with active ongoing development. First is the trunk of the git repository. This is the main development stream, where all new work and work for future releases is done.

Second is the stable bugfix branch for the latest full release. It is created around the time of the release. The branch will be named for the release version, such as “server-1.9-branch” for the X server 1.9.x series of releases. 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 development 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. Update/bugfix releases will be made on an as-required basis, depending also on the availability of resources, and will generally be limited to serious bug and security fixes. New features will not usually be added in update releases.

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

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.

The X.Org X servers report a VendorRelease value that matches the X.Org version 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.

As noted above, the version reported by VendorRelease changed from the window system version to the X server version starting in the xorg-server 1.3 release.

For all X.Org development and release versions using this 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);
	}
    }