The transition from the 4.x branch of FreeBSD to 5.x. 5.x had all kinds of problems and then 6.x was the first release that barely got out into public use befo

The transition from the 4.x branch of FreeBSD to 5.x. 5.x had all kinds of problems and then 6.x was the first release that barely got out into public use before 7.x undercut it ... and that is the cycle we have been in ever since. 4.x had minor releases going all the way to 4.11. Nowadays, major versions generally stop at X.3 (for instance, 11.3).