National bibliography number (NBN)
The purpose of the NBN is to enable persistent resource identification and the NBN enables each entry in the national bibliography to be unambiguously referenced. It is recommended that:
- The NBA assigns an NBN to each record created for the national bibliography.
- The NBN is published as part of each entry for each resource described in the national bibliography.
- NBNs are not reused.
- NBNs of both entries are retained should it be necessary to merge duplicate entries and the NBN of the superseded entry should be marked as superseded.
Further issues for consideration:
- Guidelines adopted by each national library define when different versions of a work should be assigned the same or differing NBNs. This only applies if assignment is manual.
- No resolution system is defined for the NBN. It is suggested in the registration document that resolution would be through national bibliographic databases, or through web indexes or archives.