RE: What is at the end of the namespace?

> The HTTP 
> specification
> can only talk about those aspects of the protocol that are relevant to
> HTTP. 

You've just summed up, IMO, the whole issue in a nutshell. The
HTTP URI is relevant only to the semantics of the HTTP protocol.
And the HTTP protocol is for *access* of concrete web resources.
Thus HTTP URIs are only intended to be meaningful to processes
based on the HTTP protocol, which expect to *return* something.
Therefore HTTP URIs are not intended to denote abstract concepts.

Patrick