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9xx Fields

9xx Introduction

9xx fields

9xx fields are not part of the standard MARC 21 format. OCLC has defined these 9xx fields for use by the Library of Congress and for internal OCLC use: 936, 938, 956, 987, 989, and 994. Fields 901-907, 910, and 945-949 have been defined by OCLC for your local use and will pass OCLC validation. The remaining 9xx fields may also be locally defined by your library, but may not pass OCLC validation.

OCLC services

OCLC services use some 9xx fields for processing. OCLC does not retain these fields in the WorldCat record. For example, field 951 is used for agent specific data for cataloging agent authorizations. This manual does not include descriptions of these fields.

The WorldCat Cataloging Partners, and other services, also use some 9xx fields to supply nonbibliographic information. Because WorldCat Cataloging Partners 9xx fields are defined by agreement between a library and a vendor, this manual does not include descriptions of these fields. OCLC removes WorldCat Cataloging Partners-defined 9xx fields from WorldCat records. You may still see 9xx fields that are not defined in WorldCat records. These fields will need to be removed before replacing the WorldCat record.


9xx fields are OCLC-defined and therefore not included in MARC 21 Format for Bibliographic Data.

This page last revised: August 29, 2020