Wayland and Weston 1.6.0 released

I'm also not sure why the twm comparison wouldn't be spot-on, Weston is a fully-functional demo compositor that comes with the Wayland, much like twm is a fully-functional demo window manager that comes with X. In both cases you probably use something else but it's there if you want it and makes a reference of how it's supposed to work.

Most people! I don't know how anyone can summon the requisite chutzpah to speak on the behalf of "most people." My libertarian tendencies are sending up red flags.

In any case, most people don't even know that website exists, so it's unlikely it represents their expectations, at least not at that level of detail.

Seems I'm not most people. Reality has led me to base my expectation on the program in question and its history of version number use. For Firefox, Chrome and similar things I don't expect API breaks with bumps in the major versions, I just expect those numbers to get higher on a roughly regular, date-based release schedule. With other programs I usually expect major new functionality if the major version number is bumped – but again not necessarily broken APIs (whatever the API constitutes for e.g. GUI programs).

And then there's Linux which, as someone already mentioned, seems to have one of the best user-space ABIs around and bumps the major version number whenever Linus thinks it's time for it.

semver.org is a nice theoretical concept for programmers, but reality doesn't care. Nor do non-technical users as far as my experience with them goes – they just expect that newer <=> higher version number. They also often hope that higher version number means fewer bugs, but we all know how true that is ;)

An odd minor version means a development release and an even minor version is a stable release, except for when it's KDE instead of GTK where a minor of 0 indicates an alpha release and double digits means usable but EOL, or when it's Linux and a major version of 3 means the odd/even rule no longer applies, or when it's a distro where the version is commonly misinterpreted as a base-10 fraction when it's actually a YY.MM specifier, or a web browser where the version number is akin to a Unix timestamp with a granularity of six weeks and some ill-defined epoch, or the X11/OS X variant where the major version changes so infrequently it becomes part of the name itself, or glibc from the dark ages where there were no versioned releases at all, or when the length of the version number is directly proportional to bugs fixed as in TeX/Metafont, or when major versions simply disappear for marketing reasons as in Netscape and PHP, or ...

Most people (I'd like to say "all", but threads like this give me doubt) are human beings, not mindless automatons. They expect version numbers to have *useful mnemonics*.

1.6 means there's been six large updates since the project declared itself usable to a general audience. It means programs built on 1.5 likely still work. I didn't have to go memorise the meaning of those numbers from some dry spec on a distant website to understand that.

Waving a spec around is not a substitute to RTFM. Which — had it been done by the OP in the first place — would prevent this entire comment thread from existing, because as others have helpfully pointed out, that technically-correct pedantry up there isn't even factually correct. That makes it doubly worthless.