Question about version numbers

to move to Version 11, apple would have to do a HUGE almost completely re-write type of change to the OS

the 10.1 .2 .3 etc are major updates as well, just not complete system rewrite

apple uses 10.3.1, 10.3.2 as the minor updates, currently we are on 10.3.8 so its the eight update to 10.3

 

And then to confuse things further...

A lot of open-source software - the sort of thing you find in fink, some of which does get ported to use Aqua natively instead of X11 - uses a different scheme. The first number is the major revision, like you'd expect, and the second number is still the minor revision. BUT if the minor revision is an even number (.0, .2, etc.) it is part of the "stable" release set, while odd minor numbers (.1, .3, and so on) are considered unstable "testing" trees - pre-releases for the future stable release that will have the next even number up.

So for example Gimp 2.0.2 would be considered a stable release; while Gimp 2.1.4 would be an unstable development release, focused on getting new features working for the eventual 2.2.x stable releases.

I think this practice started with the Linux kernel, but I could be wrong. In any case many (but not all) open-source software projects follow this scheme.