Looks like I'm late to the game on this: but I'm looking for something similar, and it's a fair guess that you and I are not the only people who will ever look for this information.
To the best of my ability to search, there is NO definitive language reference document for Jet-SQL on any of Microsoft's websites.
There is a list of Jet-SQL keywords here:
http://support.microsoft.com/kb/248738
Predictably this has no hyperlinks to descriptions and specifications of the keywords' underlying functionality.
The closest I've got is a Google result for someone else's search:
http://office.microsoft.com/en-us/support/results.aspx?ctags=CH010072899
However, this is not the answer you wanted: it's just another 'bits and pieces' selection - not a definitive language reference. It may help you (or rather, later searchers, like myself) by filling in the gaps, so it's not entirely useless.
It is possible that your efforts to answer your own question have come up with the missing data in a convenient format. If so, you would perform a valuable service to the developer community by posting a follow-up answer with a link.
It is entirely possible that 'Stop searching, it isn't there' is the most useful answer available today: disappointing, but helpful if others heed the warning and waste less of their time.
I would be delighted if a fellow Stack Overflow memnber were to contradict my assertion that Microsoft do not publish a definitive language specification for Jet SQL. However, I doubt that this is likely: MSDN is a collection of dead-ends and 'shallow graves' - documents that lead nowhere to related information, and information 'documented' by gravediggers who have hidden uncounted bodies of data so they will only ever see the light of day if someone knows exactly where to dig.