Subfield $0 contains the system control number of the related authority record, or a standard identifier such as an International Standard Name Identifier (ISNI).  The control number or identifier is preceded by the appropriate MARC Organization code (for a related authority record) or the Standard Identifier source code (for a standard identifier scheme), enclosed in parentheses.  In the latter case, the parenthetical "(uri)" is redundant and should not be included if the identifier is given in the form of a Web retrieval protocol, e.g., HTTP URI, which is self-identifying.

See MARC Code List for Organizations for a listing of organization codes and Standard Identifier Source Codes for code systems for standard identifiers.  Subfield $0 is repeatable for different control numbers or identifiers.

Subfield $0 is to be used for recording URIs which represent objects in RDF triple statements.

To return:

Use the key.

See also:

Appendix A:  Control Subfields