648 Subject Added Entry - Chronological Term

Field definition and scope:

Field 648 contains a subject added entry in which the entry element is a chronological term.

Subject added entries are assigned to a bibliographic 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).

The National level record requirement for this field is Mandatory if applicable.

Field 648 is repeatable.

Guidelines for applying content designators:

The content designators identify the subelements occurring in chronological terms and subdivisions.

For indicator and subfield code definitions and examples, National-level (NLR) and Minimal-level (MLR) record requirements, and designator repeatability, see table below:

Position	Description	NLR	MLR	Repeatability
Field 648	Subject Added Entry - Chronological Term	A	O	R
Indicator:
First	Undefined; contains a blank	M

Second	Thesaurus	M
0	Library of Congress Subject Headings	A
1	LC subject headings for children's literature	A
2	Medical Subject Headings	A
3	National Agricultural Library subject authority file	A
4	Source not specified	A
5	Canadian Subject Headings	A
6	Répertoire de vedettes-matière	A
7	Source specified in subfield $2	A

Subfield code:
$a	Chronological term	M	O	NR
$v	Form subdivision	A	O	R
$x	General subdivision	A	O	R
$y	Chronological subdivision	A	O	R
$z	Geographic subdivision	A	O	R
$0	Authority record control number or standard number	O	O	R
$1	Real World Object URI			R
$2	Source of heading or term	A	O	NR
$3	Materials specified	O	O	NR
$6	Linkage	A	O	NR
$8	Field link and sequence number	O	O	R

Input conventions:

Display constant

Content designator history:

First Indicator - Type of date or time period [new, 2013]

Values # - No information provided [new, 2013]

0 - Date or time period covered or depicted [new, 2013]

1 - Date or time period of creation or origin [new, 2013]

Prior to 2013, the first indicator was undefined.

First Indicator - Type of date or time period [obsolete, 2014]

Values # - No information provided [obsolete, 2014]

0 - Date or time period covered or depicted [obsolete, 2014]

1 - Date or time period of creation or origin [obsolete, 2014]

The definition of the first indicator was repealed in 2014 when the new field 388 (Time Period of Creation) was approved.

Subfield $0 - Authority record control number or standard number [new, 2007]

Subfield $0 - Authority record control number [redefined, 2010]

Subfield $1 - Real World Object URI [new, 2017]