Note that the Introspection file had it's own URI that
was seperate from the other protcol URIs.
Just curious, if it weren't for the history, what would be the
advantage of separating the PostURI from the introspection URI? The
"feed" is a resource; in one case we're posting to it, in another case
we're getting information about it. Is it the distinction between
"getting a representation of" and "getting data about"?