Looking around on the web for a decent (i.e. formal) specification of RSS, I found this page.
It looks like not only is there no formal specification for RSS 2.0, there are in fact several indistinguishable but incompatible versions all calling themselves RSS 2.0. Sigh. How the fsck am I supposed to figure out how to make my RSS valid if there’s no formal spec for it, much less a DTD?