At http://www.intertwingly.net/wiki/pie/PaceAPPCategories
Based on PaceCategoryListing2. In an introspection document, you either have an href= or you don't. If not, you contain atom:category elements directly. If you do, it has to point to a Categories document, whose root is <app:categories> with <atom:category> children. The only thing that's not obvious is that <app:categories>, when it's the root of a Categories doc, can have a @scheme attribute to provide a default, if you want a couple of hundred categories and not to provide the [EMAIL PROTECTED] for all of them.
This seems to be about the minimum I can think of that would give APP category listing, without trying to stretch too far or solve the whole problem.
-Tim
