A Uniform Resource Name (URN) is a Uniform Resource Identifier (URI) that uses the urn scheme. URNs are globally unique persistent identifiers assigned within defined namespaces so they will be available for a long period of time, even after the resource which they identify ceases to exist or becomes unavailable.[1] URNs cannot be used to directly locate an item and need not be resolvable, as they are simply templates that another parser may use to find an item.