For the past six major versions, we've used M.0.m.b where M is the major version, m is the minor version, and b is the build number. So released versions included 6.0.2, 7.0.1, ..., up to 11.0.0. Don't ask why the second number is always 0; I've asked a number of times and nobody really knows. We haven't had a non-zero there since 5.5 was released in 1996.
