The concept of "AnyName/AnyNamespace" in Multiname is (apparently) a construct that is really useful only to E4X code (to support wildcards), but this isn't well-documented anywhere in our code or specs. We should (at a minimum) add documentation to the Multiname class about when and where these variants are acceptable. For extra credit, we could examine whether it's feasible to move the "Any" functionality to some Multiname subclass, so that it's only possible to express this functionality to the E4X code that's expecting it (thus changing a runtime/assertion failure into a compiletime failure).

All the bells and whistles of Multinames needs to be fleshed out in "The structure of the ActionScript Virtual Machine" in avmspec, perhaps even its own toplevel section.