750 Index Term - Topical (R) (Variable Data Field)
Field definition and scope: This field contains a topical term used as an index term that supplements terms derived from data in the USMARC classification record. The term may be referred to in the classification number and caption in field 153 (Classification Number). The field may be used to link a classification number with a related controlled subject heading. Topical index terms may consist of general subject terms including names of events or objects. The 750 field provides access to classification numbers according to generally accepted thesaurus-building rules [e.g., Library of Congress Subject Headings (LCSH), Medical Subject Headings (MeSH)]. The values in the second indicator position or the data in subfield $2 (Source of heading or term) identify the subject heading system or thesaurus used by an institution to formulate the topical index term. To be included in this field, a topical index term must match the controlled heading, including any subdivisions. Index terms not controlled by a thesaurus are contained in field 753 (Index Term - Uncontrolled).
Field 750 is repeatable.
Guidelines for applying Content Designators: [Guidelines for applying subfields $i and $w are provided below. Guidelines for applying the remaining content designators and input conventions are provided in the USMARC Format for Bibliographic Data: field 650 (Subject Added Entry - Topical Term).]
Indicators
First Level of subject
# No information available (# indicates a blank )
0 No level specified
1 Primary subject
2 Secondary subject
Second Subject heading system/thesaurus
0 Library of Congress Subject Headings/LC authority files
1 LC subject headings for children's literature
2 Medical Subject Headings/NLM authority files
3 National Agricultural Library subject authority file
4 Source not specified
5 Canadian Subject Headings/NLC authority file
6 Répertoire des vedettes-matière/NLC authority file
7 Source specified in subfield $2
Subfield Codes
Main term portion:
$a Topical term or geographic name as entry element (NR)
$b Topical term following geographic name as entry element (NR)
Subject subdivision portion:
$x General subdivision (R)
$y Chronological subdivision (R)
$z Geographic subdivision (R)
Control subfields:
$i Explanatory text (R)
$w Authority record control number (R)
$2 Source of heading or term (NR)
$3 Materials specified (NR)
Related USMARC fields or documents:
USMARC Format for Bibliographic Data:
USMARC Code List for Organizations
See also:
