Experience has shown that identifiers associated with persistent names have properties and requirements that may be somewhat different from identifiers associated with the locations of objects. This is especially true when such names are expected to be stable for a very long time or when they identify large and complex entities. In order to allow Uniform Resource Names (URNs) to evolve to meet the needs of the Library, Museum, Publisher, and Informational Sciences communities and other users, this specification separates URNs from the semantic constraints that many people believe are part of the specification for Uniform Resource Identifiers (URIs) specified in RFC 3986, updating that document accordingly. The syntax of URNs is still constrained to that of RFC 3986, so generic URI parsers are unaffected by this change.