Mac OSX and SUSv3

Anybody know the story of Mac OSX vis-a-vis the Single Unix spec?
Neither Google nor internal searches at apple.com turn up anything
useful other than some newsgroup posting indicating that older OSX
releases weren't conformant, which is no big surprise.

I did see some talk that the upcoming "Tiger" release will have 64-bit
support but again no hard data other than that it's traditional LP64.

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Thanks,
M.Biswas