[snip]
I would cast this as
<collection href="...">
<a:title>foo</a:title>
<accept>...</accept>
<a:category scheme="http://example.org/feature"; term="http://.../a"; />
<a:category scheme="http://example.org/feature"; term="http://.../b"; />
<e:f />
</collection>
Then you can look for categories of collections in a certain
scheme if you want to enumerate the features of a collection, but
you can also express different classes of collection properties
by associating each class with a scheme. This seems like it
should cover uses of Atompub in non-publishing context; an issue
that also came up recently.
Regards,