Second Life Viewer Versioning
The Second Life Viewer uses a four-place version convention that is common to the software industry. The four places in the w.x.y.z version string correspond to Major.Minor.Patch.Revision, and combine to indicate the nature of each release. Information describing circumstances under which each place is incremented has been provided in the following sections.
Note: Individual Second Life viewer versions may be formatted as either "w.x.y.z" or "w.x.y (z)". In 'Help > About Second Life', as well as in the release notes, we have standardized on the "w.x.y.z" format, but either version format is acceptable.
W.x.y.z - Major Revision
The first place, or Major version, in each version number effectively represents the "generation" of Second Life. Changes in the Major revision are reserved for comprehensive changes in the way Second Life looks and/or functions.
This is usually incremented only for changes that introduce significant incompatibilities (if you are not up to date, something important in Second Life will not work correctly for you).
w.X.y.z - Minor Revision
The second place is incremented when the version has added significant but essentially compatible new features and enhancements, or releases in which very important bugs are fixed.
w.x.Y.z - Patch Revision
The third place, or Patch version, is incremented for releases whose changes are relatively minor.
w.x.y.Z - Build
The final place in the viewer version contains a Build number unique to each release (produced by our internal build system). Updates (rebuilds) to a particular viewer project will usually differ only in this last number.
Second Life Server Versioning
Prior to September 2010, the server was versioned much like the viewer. Since then we have moved to a different format; the versioning scheme is simple:
[2-digit year].[2-digit month].[2-digit day].[build number]
The date in the version is the date that the code was compiled. The build number is a unique, incrementing, number for each revision produced by our internal build system.