253 Complex See Reference

Field definition and scope:

Field 253 contains explanatory text and the Classification number referred to that are required when a see reference relationship exists between classification numbers that cannot be adequately conveyed by one or more simple cross references generated from a 453 (Invalid Number) or 553 (Valid Number) tracing field. A see also reference that directs the user to a related number is contained in field 353 (Complex See Also Reference).

A cross reference display may be constructed from the 153 and 253 fields of the record. Field 153 (Classification Number) contains the classification number or span referred from. Field 253 contains the explanatory text for the reference and the other classification number(s) or span(s) referred to. When several reference notes are associated with a classification number, each may be recorded in a separate field or they may be combined and recorded in a single field. References providing information about use of numbers discontinued in whole or in part for a topic and about topics relocated in whole or in part to other numbers are contained in field 685 (History Note).

Field 253 is repeatable.

Guidelines for applying content designators:

For indicator and subfield code definitions and examples, and designator repeatability, see table below:

Position	Description	Repeatability
Field 253	Complex See Reference	R
Indicator:
First	Type of reference
0	See reference
1	Standard subdivisions do-not-use reference
2	Class elsewhere reference

Second	Undefined; contains a blank

Subfield code:
$a	Classification number referred to - single number or beginning number of span	R
$c	Classification number referred to - ending number of span	R
$i	Explanatory text	R
$y	Table sequence number for internal subarrangement or add table	R
$z	Table identification	R
$6	Linkage	NR
$8	Field link and sequence number	R

Input conventions:

Order of subfields

Invalid classification numbers

Number spans

Display of classification numbers and captions

Display constants

Scheme-specific conventions:

Library of Congress Classification for X53 fields

Library of Congress Classification for field 253

Dewey Decimal Classification for X53 fields

Content designator history:

Subfield $y - Table sequence number for internal subarrangement or add table [new, 2008]