URN in Objective-C?...

Is there an official or de-facto common URN NID for private unregulated use?...

JAXB: How do I annotate classes so that they belong to different namespaces?...

Explain BNF syntax for NID in RFC 2141...

Using DNS as a URN resolver...

URN for MIME Type...

RDF and uuid. why no urn schema?...