Format is [Y] Y.MM [. [V] [versiontype] ]

Y.MM and YY.MM are main versions and finals.
main versions will likely be released at the first of the month since any subversion will be newer.
Single digit years must begin with a 7, 8 or 9.
IE 08.12 is identical to 8.12  =  _wnt5_x86-32_0812.7z and _wnt5_x86-32_812.7z

V is a Subversion.
A subversion is always newer than its main version
IE 08.12.x is newer than 08.12 = _wnt5_x86-32_8121.7z is newer than _wnt5_x86-32_812.7z
a subversion is the 'V' in YY.MM.V
- The Version value is only one place / character long.
- The only valid values are numbers 1 through 9.
- sub versions are compared if the main versions match for two files.
- a main version with only a subversion is a final yy.mm.v or yy.mm  = final

Versiontype
there are four types
1 Nightly
2 Beta
3 Release candidate
4 Final

1 A nightly is any Number that follows the sub version number
IE  8.12.11 or 8.12.1   =   _wnt5_x86-32_81211.7z a nightly is older than _wnt5_x86-32_8121.7z     a final
     8.12.11 or 8.12.130 =  _wnt5_x86-32_81211.7z a nightly is older than _wnt5_x86-32_812130.7z a nightly also

2 A beta has a b in the first location past the version and may or may not be followed by a number (zero assumed).
IE  8.12.11 or   8.12.1b1  =  _wnt5_x86-32_81211.7z a nightly is older than _wnt5_x86-32_8121b1.7z   a beta
     8.12.1b1 or 8.12.1b30 =  _wnt5_x86-32_8121b1.7z a beta  is older than _wnt5_x86-32_8121b30.7z a beta also

3 A release candidate has an rc in the first location past the version and may or may not be followed by a number (zero assumed).
IE 8.12.1b or    8.12.1rc1  =  _wnt5_x86-32_8121b.7z a    beta is older than _wnt5_x86-32_8121rc1.7z  a release candidate
    8.12.1rc1 or 8.12.1rc30 =  _wnt5_x86-32_8121rc1.7z an RC is older than _wnt5_x86-32_8121rc30.7z a release candidate  also

4 A final will never have any versiontype values included

8.12.1rc30 or 8.12.1   =  _wnt5_x86-32_8121rc30.7z  a Release Candidate is older than  _wnt5_x86-32_8121.7z   a final

A typical month in the life of a pack might look like

8.12        We just finished the November pack and it is Dec 1 and we release a 'main' version Y.MM

8.12.101     Dec   1 we are starting on our second release and our first subversion '1' and add the date '01' a nightly
8.12.103     Dec   3 we are addressing some reported issues.  a nightly
8.12.107     Dec   7 we are adding new drivers. a nightly
8.12.1b12   Dec 12 we are Happy with it. a beta
8.12.1rc15  Dec 15 we anounce it on the news page for release testing to all readers. a true release candidate.
8.12.1        Dec 15  we just couldn't wait any longer. ahhh what the heck, it's final!
8.12.216     Dec 16 we should have waited... starting third release and our second subversion '2' and add the date '16' a nightly
8.12.217     Dec 17  minor issue
8.12.218     Dec 18  minor issue
8.12.2b19   Dec 19 seems solid
8.12.2rc20  Dec 20 News page anouncement
8.12.2rc21  Dec 21 all good reports for days... one final issue corrected.
8.12.2        Dec 25 we release our third final for the month and a merry christmas to all
8.12.326    (yeah right!)

Notes:
Never put the dots in the actual file names.  It just makes them easier to read here and is how base will display them
b and rc are recognized in lowercase only
older versions of base ( <= 8.12.2) will not support a two digit year YY.MM format this will start with the next release 

Copied from testing team forum
originaly posted and stickied 2008-12-02 05:43:57