Uniform Resource Name
(URN, previously Uniform/Universal Resource Number) 1. Any URI which is not a URL.
2. A particular scheme which is currently (1991-4) under development by the IETF, which should provide for the resolution using Internet protocols of names which have a greater persistence than that currently associated with Internet host names or organisations (as used in URLs). Uniform Resource Names will be URI schemes that improve on URLs in reliability over time, including authenticity, replication, and high availability.
When defined, a URN in sense 1 will be an example of a URN in sense 2.