Re: URNs for SYSTEM identifiers

>IANA apparently intends to use URNs for SYSTEM identifiers.

No.  Michael Mealling is proposing to register URIs for DTDs and schemas
and RDF schemas and "namespaces" occurring in IETF standards.  He is
also proposing to create a URN name space for use as SYSTEM identifiers.
But this is a proposal in the IETF -

  http://www.ietf.org/internet-drafts/draft-mealling-iana-xmlns-registry-00.txt

 - it is nowhere near being a standard, and it isn't a proposal from
IANA.  Though it's a good idea ...

regards, Terry