RFCs and PMIDs are supported.
Ah, so I see. Is all this documented anywhere?
Do you mean formally or informally ?
If you mean informally, then: http://en.wikipedia.org/wiki/Wikipedia:PMID http://en.wikipedia.org/wiki/Wikipedia:ISBN (couldn't see one for RFC, as [[WP:RFC]] is about a Wikipedia process).
If you mean formally, then the answer I think is no. (In practice this means that the corner-case behaviour can fluctuate as the implementation changes - E.g. up until 2 days ago "ISBN ----" rendered as "<p>ISBN</p>", and now it renders basically as "<a href='Special:Booksources'>ISBN ----</a>"). If you want this level of detail though the source seems to the best reference: http://svn.wikimedia.org/viewvc/mediawiki/trunk/phase3/includes/Parser.php?v... Search for "doMagicLinks" and "magicLinkCallback".
All the best, Nick.