Dear Jeremy, Jeff, Gary,
You are right, that the purpose of the collection definition of the
collection WG is to set a minimum bar to get as much specificity as
necessary in order to outline an API at the end, that is able to handle
specific queries on collections.
The question whether DOs might be identified by a formal ID, or by a
query, or by some other method, is currently not really solved in this
context, and the idea to construct a collection by some function is
rather new in the collection WG.