| First Indicator | Second Indicator |
|---|---|
| Undefined # - Undefined |
Thesaurus 0 - Library of Congress Subject Headings 1 - Library of Congress Children's and Young Adults' Subject Headings 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 |
| Subfield Codes | |
|---|---|
|
Main term portion
Subject subdivision portion
|
Control subfields
|
Subject entry in which the first element is a chronological term.
Subject added entries are assigned to a community information record to provide access according to generally accepted thesaurus-building rules (e.g., Library of Congress Subject Headings (LCSH), Medical Subject Headings (MeSH), Faceted Application of Subject Terminology (FAST)). Field 648 may be used by any institution assigning subject headings based on the lists and authority files identified in the second indicator position or in subfield $2 (Source of heading or term).
Subelements occurring in chronological terms and subdivisions.
First Indicator - Undefined
Undefined and contains a blank (#).
Second Indicator - Thesaurus
Thesaurus or authority file from which the heading came.
Added entry conforms to the Library of Congress Subject Headings (LCSH) and the Name authority files. LCSH is maintained by the Library of Congress. Use of Value 0 requires that the heading is appropriate for use in LCSH. Conforms to LCSH is defined as:
Subject added entry conforms to the Library of Congress Children's and Young Adults' Subject Headings used for the Library of Congress Children's and Young Adults' Cataloging (CYAC) Program and is appropriate for use according to CYAC guidelines.
Subject added entry conforms to the NLM authority files, Medical Subject Headings (MeSH). MeSH is maintained by the National Library of Medicine. Use of value 2 requires that the field is appropriate for use in MeSH.
Subject added entry conforms to the National Agricultural Library subject authority file. Use of value 3 requires that the field is appropriate for National Agricultural Library subject heading purposes.
Subject added entry conforms to a controlled list that cannot be identified by by second indicator values 0-3, 5-6 or by a code in subfield $2. Field 653 (Index Term-Uncontrolled) is used to record terms that are not derived from controlled subject heading lists.
Subject added entry conforms to Canadian Subject Headings.Canadian Subject Headings is maintained by Library and Archives Canada.
Subject added entry conforms to the Répertoire de vedettes-matière that is maintained by the Bibliothèque de l'Université Laval.
Subject added entry conforms to a set of subject heading system/thesaurus building rules other than that specified by one of the other defined values and for which identifying codes are given in subfield $2. Codes from: Subject Heading and Term Source Codes.
$a - Chronological term
| 648 | #7$a1900-1999$2fast | ||||||||
| 648 | #7$a1862$2fast | ||||||||
| 648 | #7$a1800-1899$2fast | ||||||||
$v - Form subdivision
Form subdivision that designates a specific kind or genre of material as defined by the thesaurus being used. Subfield $v is appropriate only when a form subject subdivision is added to a main term.
$x - General subdivision
Subject subdivision that is not more appropriately contained in subfields $v (Form subdivision), $y (Chronological subdivision), or $z (Geographic subdivision). Subfield $x is appropriate only when a general topical subdivision is added to a main term.
$y - Chronological subdivision
Subject subdivision that represents a period of time. Subfield $y is appropriate only when a chronological subject subdivision is added to a main term.
$z - Geographic subdivision
Geographic subject subdivision. Subfield $z is appropriate in field 648 only when a geographic subject subdivision is added to a main term.
$0 - Authority record control number or standard number
See description of this subfield in Appendix A: Control Subfields.
$1 - Real World Object URI
See description of this subfield in Appendix A: Control Subfields.
$2 - Source of heading or term
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 $2).
Code from: Subject Heading and Term Source Codes.
| 648 | #7$a1900-1999$2fast | ||||||||
| 648 | #7$a1862$2fast | ||||||||
| 648 | #7$a1800-1899$2fast | ||||||||
$3 - Materials specified
Part of the described materials to which the field applies.
$6 - Linkage
See the description of this subfield in Appendix A: Control Subfields.
$8 - Field link and sequence number
See the description of this subfield in Appendix A: Control Subfields.
Display Constant - The dash ( - ) that precedes a subject subdivision in an extended subject heading is not carried in the machine-readable record. It may be system generated as a display constant associated with the content of subfield $v, $x, $y, and $z.