You can always use something like <#abc> or :abc for terms of the document being described or just an extra graph that is just private and not shared like <http://comp.com/abc>. Anyhow I don't think this is what is missing to make the semantic web work.

I remember the semantic web people telling me when asking about URN they said "we don't use those anymore", so that is that, and the story of the semantic web.