in the example of "major.minor.build.revision" we abandoned the revision number and use the latest to indicate a beta (where beta would mean "not fully tested"):
1.2.1.0 -> normal release
1.2.1.1 -> beta release
Now I hear you say "what?? no revision number? how do you track bugs then", as I know people/companies sometimes tend to match the "revision" number with their VCS especially when using svn. At least two options: get rid of the build number instead and keep the revision (do you really need more than major.minor for the actual version?), or what we do is tag the repository with the version number for each release which is the other way around but has the same effect + we feel clients shouldn't need to know what the amount of commits in a VCS is.