Core/ MAGIRT Cartographic Resources Cataloging Interest Group

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Discusses the basic issues relating to bibliographic control of maps and related materials. Discusses rules and standards covering such cataloging, as well as application of the rules and principles both in general and in response to specific problems, and various practicing options.

This group is part of Core's Metadata & Collections Section.

Additional Description Convention Source Codes Exempted from DDR

  • 1.  Additional Description Convention Source Codes Exempted from DDR

    Posted Nov 18, 2022 03:09 PM

    Most days, OCLC's Duplicate Detection and Resolution (DDR) software runs behind the scenes of WorldCat, searching for and merging duplicate bibliographic records.  There are, however, several categories of records that are deliberately exempted from DDR processing.  Among those exempted categories are all records with dates of publication up and to and including 1829, and all records identified in field 040 subfield $e as being cataloged under any of the descriptive cataloging conventions commonly used for rare and archival materials.  OCLC determined these specifications in consultation with the Bibliographic Standards Committee (BSC) of the Rare Books and Manuscripts Section (RBMS) of the Association of College and Research Libraries (ACRL), a division of the American Library Association (ALA).

    OCLC is pleased to announce that the following seven MARC Description Convention Source Codes that are appropriate for rare and archival materials have now been added to the existing list of 25 exempted codes.

    Most of these seven codes are relatively recent additions to the MARC Description Convention Source Codes list.

    The complete list of 32 MARC Description Convention Source Codes that are now exempt from DDR processing in WorldCat when they appear in field 040 subfield $e are:

      • amim
      • amremm
      • appm
      • bdrb
      • cco
      • cgcrb
      • dacs
      • dcarlisnaaf
      • dcgpm
      • dcrb
      • dcrmb
      • dcrmc
      • dcrmg
      • dcrmm
      • dcrmmss
      • dcrmr
      • dcrms
      • dmbsb
      • enol
      • estc
      • fiafcm
      • gihc
      • hmstcn
      • iosr
      • kam
      • nmxcmdf
      • ohcm
      • rad
      • rna
      • rnab
      • vd16
      • vd17

    The full citations for all the codes, and links to many of the descriptive conventions themselves, may be found in the MARC Description Convention Source Codes document maintained by the Library of Congress.



    Jay Weitz


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    Jay Weitz
    Senior Consulting Database Specialist
    Online Computer Library Center