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.

Note:  Subfield $0 is sometimes referred to in the field descriptions as Record control number.

Examples:

084  0#  $alcc  [Library of Congress Classification]

153  ##  $aBS580.M6$hThe Bible$hGeneral$hWorks about the Bible$hMen, women and children of the Bible$hBiography$hIndividual Old Testament characters, A-Z$jMoses

700  00  $aMoses$c(Biblical leader)$0(DLC)n##79058331

084  0#  $alcc  [Library of Congress Classification]

153  ##  $aHG3881.5.158$hFinance$hForeign exchange. International finance$hInternational finance. International monetary system. International banking$hIndividual international financial institutions, A-Z$jInternational Monetary Fund

710  20  $aInternational Monetary Fund$0(DLC)n##81052755

084  0#  $alcc  [Library of Congress Classification]

153  ##  $aPR1588$hEnglish literature$hAnglo-Saxon literature$hIndividual authors and works$hBeowulf$hCriticism$jLanguage, grammar, etc.

730  00  $aBeowulf$xLanguage$0(DLC)sh#85013267

See also:

Appendix A:  Control Subfields