My rules? Hahaha, right...
What!? That's not what I said at all. I said nothing about number changes, I said point releases
1.0 -> 1.1 is what is considered a point release in the software world
1.1 -> 2.0 is what is considered a major release
Windows 95 -> 98 would be a major release
OS 9 -> OS X would be a major release
Anything less is, well, not a major release regardless of how Apple spins it. I don't know why this is something offensive to all of you, it wasn't an insult. I only brought it up to him because you have less to worry about when it comes to compatibility when you're dealing with point releases, because core components are less likely to change. Just look at what moving from XP to Vista broke, or OS 9 to X
Sure. Windows 2000 to XP was a major release, but when you look at the version numbers, it only was a point release (5.0 to 5.1). Same happened with Vista and 7 - 6.0 to 6.1.
And when you look at most open source projects, your numbering schemes don't work at all anymore. Most open source projects still have not reached version 1.0, even when they've been around in stable releases for years.
There are no general rules for version numbers, everybody has their own numbering scheme and in Apple land, every new 10.x release is a major release and 10.x.y releases are point releases.