Academic journal article Information Technology and Libraries

The Need for Machine-Readable Authority Records for Topical Subdivisions

Academic journal article Information Technology and Libraries

The Need for Machine-Readable Authority Records for Topical Subdivisions

Article excerpt

This paper recognizes the limitations of the existing file of Library of Congress subject authority records for subject heading assignment and validation. It makes recommendations for a new machine-readable file of authority records for topical subdivisions and for enhancements to the existing subject authority file. The recommended changes would enable online systems to assist in subject heading formulation and verify, with limited assistance by human intermediaries, the individual components of subdivided headings. A study of subdivided subject headings in a large bibliographic database forms the basis of the recommendations.

No comprehensive list of topical subdivisions is yet available in machine-readable form. The machine-readable Library of Congress Subject Headings (LCSH-mr) contain a few records for subdivisions when subdivisions are the same as main headings or see references. LCSH-mr also contain subdivided headings, but the subdivisions in these headings are only authorized with the particular main headings to which they are appended. Generally, catalogers consult the printed publication Subject Cataloging Manual: Subject Headings (SCM:SH) to find appropriate subdivisions to append to subject headings. (1)

The availability of machine-readable records for topical subdivisions would enable catalogers to "cut" subdivisions from authority records and "paste" them into bibliographic records. In online cataloging systems, such a capability would reduce typographical errors and minimize the assignment of unauthorized subdivisions. It would not, however, enable systems to determine automatically whether the individual components of subdivided headings are correctly formulated and authorized with the particular main heading. Additional information needs to be incorporated into machine-readable subdivision records to enable systems to perform automatic verification of subdivided subject headings.

The purpose of this paper is to demonstrate the need for machine-readable authority records for topical subdivisions to improve the quality and accuracy of subdivision assignment. It describes the extent to which assigned subject headings in a large bibliographic database are subdivided by topical subdivisions and the source of those subdivisions in printed and online cataloging tools. It makes recommendations for machine-readable authority records for subdivisions and for enhancements to existing files of subject authority records. Such enhancements would enable online systems to verify automatically whether the individual components of subdivided headings are correctly formulated and authorized with the particular main heading.

PREVIOUS CALLS FOR A SUBDIVISIONS FILE

The most widely used subject authority file for subjects is the LCSH-mr. Since early 1986, the Library of Congress' Cataloging Distribution Service (CDS) has made LCSH-mr available to subscribers in the form of a cumulative master tape and a weekly update service. Only one-third of the subject headings in this file are subdivided. (2) In contrast, about two-thirds of the assigned subject headings in bibliographic databases are subdivided. (3,4) The existing subject authority file is of limited use for assignment and validation of subject headings because of the many options available to catalogers for adding subdivisions to the headings printed in LCSH. (5)

Since the early 1980s, the library community has called for machine-readable authority files to aid in subject heading assignment and validation. Underlying such calls is indecision about the form of these files. Should these files consist of subdivision records or unique strings of subdivided headings? Such indecision is evident in the recommendation of an ALA subcommittee that encourages the Library of Congress (LC) to conduct research to determine whether separate authority records should be created for every unique heading or whether "separate files of authorized free-floating subject subdivisions would suffice. …

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