http://www.rfc-editor.org/rfc/rfc2611.txt
RFC 2611: URN Namespace Definition Mechanisms, L. Daigle, D. van Gulik, R. Iannella, P. Faltstrom1999-06-01T23:00:00-00:00This document lays out general definitions of and mechanisms for establishing URN "namespaces". This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.