1XX Classification Numbers and Terms - General Information (Variable Data Field)
A USMARC classification record contains either a field 153 (Classification Number) or a field 154 (General Explanatory Index Term). Field 153 is used if the record is an authority for a classification number or span and its associated caption and caption hierarchy. Field 154 is used if the index term cannot be associated with one classification number or number span of an index-term-only record (008/06 Kind of record, code c). An index term that has an associated classification number is contained in one of the 70X-75X Index Term fields in a schedule or table record (008/06, code a or b).
Three types of classification numbers are identified in 008/07 Type of classification number:
Single number - A single classification number. In an X53
field, the elements of a single number may be contained in either one
subfield $a (Single number or beginning number of span) or in multiple
subfields $a. The division of a single number into elements is determined
by classification-scheme-specific conventions.
Defined number span - A range of classification numbers that is
defined by a separate table or subarrangement.
The beginning number element of the span in an X53 field is contained in
subfield $a; the ending number element is contained in subfield $c
(Ending number of span).
Summary number span - A range of classification numbers that summarizes
a topic or topics. A summary number span is not defined by a separate table
or subarrangement. The numbers falling within the span are generally defined
in separate classification records.
Classification Number Usage in Bibliographic and Authority Records:
Classification numbers may be valid, invalid, or, in the case of number spans, partially valid (008/08 Classification validity). Only valid classification numbers may be contained in any of the 0XX Call Number and Classification Number fields that are defined for USMARC bibliographic and authority records. A valid number may be used either by itself or with additional letters or numbers. In the case of valid number spans, only a portion of the span may be used. A number that has been synthesized by applying a table, internal subarrangement, or add instructions to a base classification number is also valid for use in bibliographic and authority records. Only the valid portion of a partially valid number span (008/08, code b or c) may be used in bibliographic and authority records.
Related USMARC fields or documents:
084 Classification Scheme and Edition
X53 Classification Numbers - General Information
See also:
1XX Classification Numbers and Terms: Contents