MARC 21 Format for Bibliographic Data: 648: Subject Added Entry-Chronological Term (Network Development and MARC Standards Office, Library of Congress)

First - Type of date or time period: # - No information provided; 0 - Date or time period covered or depicted; 1 - Date or time period of creation or origin
Second - Thesaurus: 0 - Library of Congress Subject Headings; 1 - LC subject headings for children's literature; 2 - Medical Subject Headings; 3 - National Agricultural Library subject authority file; 4 - Source not specified; 5 - Canadian Subject Headings; 6 - Répertoire de vedettes-matière; 7 - Source specified in subfield $2

$0 - Authority record control number or standard number (R): See description of this subfield in Appendix A: Control Subfields.

$2 - Source of heading or term (NR): MARC code that identifies the source list from which the subject added entry was assigned. It is used only when the second indicator position contains value 7 (Source specified in subfield $2). Code from: Subject Heading and Term Source Codes.

$6 - Linkage (NR): See description of this subfield in Appendix A: Control Subfields.

$8 - Field link and sequence number (R): See description of this subfield in Appendix A: Control Subfields.

648 - Subject Added Entry-Chronological Term (R)