Reserved for local call number use and local definition. For interchange purposes, documentation of the structure of the 09X fields and input conventions must be provided to exchange partners by the organization initiating the interchange.
Field 090 - Shelf Location (AM) [OBSOLETE, 1977] [USMARC only]
Field 090 - Local Call Number [OBSOLETE, 1982]
Field 091 - Microfilm Shelf Location (AM) [OBSOLETE, 1977] [USMARC only]