Hi, following up http://mail.python.org/pipermail/docs/2011-February/003083.html we have a chat on #python-dev on the topic, the situation is

- all started with os.lchmod() and as.lchflags() methods not available on a Debian system
- that's because POSIX does not require those functions and then Linux systems don't provide them 
- so we then thought about clarifying, only for those 2 methods, that they might not be available with a format like "availability: some unix systems"
- then we noticed that on top of os doc there's a notice "An “Availability: Unix” note means that this function is commonly found on Unix systems. It does not make any claims about its existence on a specific operating system." and so we thought about linking every 'Availability: Unix' to that note
- or transform that not in a footnote and link every 'Availability: Unix' for functions that might not be present to that footnote.

It's enough for the conversation dump: ideas/suggestions? :)