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Cataloging and Metadata Management

Standards Used in Cataloging


Descriptive Cataloging Standards

RDA: Resource Description and Access serves as the current authority for descriptive cataloging at NLM. These rules are supplemented by the LC-PCC Policy Statements which appear in the RDA Toolkit. Bibliographic records are formatted according to MARC21 Format for Bibliographic Data. RDA has replaced the Anglo-American Cataloging Rules, 2nd ed. (AACR2) as of March 31, 2013.

Personal and corporate access points appearing in most cataloging records follow either AACR2 rules or RDA guidelines. Some records were cataloged prior to the adoption of AACR2 and thus, the headings used may reflect earlier cataloging practices. NLM has been submitting authority records to NACO (Name Authority Cooperative Program of the PCC) for its English language material since 1985. Beginning in March 2012, NLM has been submitting all authority records to NACO. The authority records are formatted according to MARC21 Format for Authority Data.

NLM applies multi-level description in the cataloging of monographs: full level descriptive cataloging, Bibliographic Standard Record (BSR)-level cataloging following the standards promulgated by the Program for Cooperative Cataloging (PCC), and NLM's minimal level or "Limited cataloging." Serials are cataloged following the CONSER Standard Record (CSR) guidelines or NLM’s minimal level cataloging standard. Details of the various levels of description used at NLM in the cataloging of monographs and serials are documented in NLM Cataloging Section: Definition of Cataloging Levels. Details of the various levels of description used at NLM in the cataloging of monographs and serials are documented in NLM Cataloging Section: Definition of Cataloging Levels.

Subject Cataloging Standards

  • Subject Headings

    The topical subject headings used in cataloging are from Medical Subject Headings(MeSH®), NLM's controlled vocabulary, which is also used in the preparation of MEDLINE®, and PubMed®. Name and title subjects are taken from the National Authority File. NLM assigns subject headings as appropriate to all materials regardless of imprint date.

  • Classification

    Medical titles generally are classified according to the National Library of Medicine Classification available online at //wwwcf.nlm.nih.gov/class/ (see also Classification and Shelflisting).

    For titles in fields peripheral to medicine, the Library of Congress classification schedules are used in full, with no modification.

    Material at NLM is not always shelved by classification number and it is possible to encounter bibliographic records that lack classification numbers entirely.

    1. Generally, for monographs shelved in the General Collection:

    • Limited level cataloging records cataloged prior to summer 1988 do not contain classification numbers. They are shelved using an alphanumeric shelving number.
    • Limited level cataloging records cataloged between 1988 and 1994 contain classification numbers without cuttering or dates. They are also shelved using an alphanumeric shelving number.
    • Full and core level cataloging records created before 1994 contain a fully shelflisted classification number and are shelved by that number.
    • Full and core level records cataloged between 1994 and June 21, 2010 contain fully shelflisted classification numbers, but are shelved by accession numbers.
    • Full and core level print records cataloged after June 21, 2010 contain classification numbers without cuttering or dates. They are shelved by accession numbers.
    • Non-print materials cataloged after 2004 contain classification numbers without cuttering or dates. They are shelved by accession numbers.

    2. Serials are classified in the form number W1 with the exceptions of: Government administrative reports or statistics (W2), hospital administrative reports or statistics (WX 2), certain publication types, e.g., directories (monographic form numbers), and bibliographies and indexes (Z).

    Before July 1988, the W3 classification number was assigned to sequentially numbered or dated monographic conferences. These congresses are now classed in the appropriate subject classification. Reports or proceedings of congresses published as serials are classified in W1 with other serials.

    NLM classes serial analytics with the serial call number. W1 and W3 serial analytics cataloged since the mid 1970s also carry an alternative subject call number provided by NLM for libraries wishing to class such publications by subject.


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Last Reviewed: May 22, 2020