Back on July 11, 2011 there was a thread about the functionality of extracting the Revision and Build numbers from a full version string (FUNCTION:Retrieve Build Version Number). At least according to what I have been able to find, I think you got it backwards. Most of the sources I have found define it as:

1st set of digits = Major Version
2nd set of digits = Minor Version
3rd set of digits = Release or revision number
4th set of digits = Build number

I wish that the above definition was, uh, definitive. Unfortunately it is not. Even within Microsoft some times the 3rd and 4th sets of digits are one way and, in another product, it is reversed (.NET has it reversed from my list above). SetupBuilder does it like .NET and reverses the 3rd and 4th sets of digits from my list.

I don't suggest you make any changes to SetupBuilder but you might want to address it in the online help and the manual. I had it backwards from what SetupBuilder does it and it eventually came back to bite me.