7XX Subfield $2 - Source of heading or term:

Subfield $2 contains a MARC code that identifies the thesaurus or authority file that is the source of the heading or term when the second indicator position contains value 7 . Subfield $2 is appropriate only in field 7XX. The source of the code is MARC Code Lists for Relators, Sources, Description Conventions that is maintained by the Library of Congress.

Examples:

008/09 d [subdivision record]

008/11 r [code indicating AAT]

185 ##$vatlases

755 #7$vatlases$0<record control number>$2aat

008/09 a [established heading record]

008/11 r [code indicating AAT]

155 ##$aatlases

785 #7$vatlases$0<record control number>$2aat

[The same heading is used both as a subject and as a subdivision term in the Art and Architecture Thesaurus.]