Form Subdivisions

Abstract

Form subdivisions have always been an important part of the Library of Congress Subject Headings. However, when the MARC format was developed, no separate subfield code to identify form subdivisions was defined. Form and topical subdivisions were both included within a general subdivision category. In 1995, the USMARC Advisory Group approved a proposal defining subfield $v for form subdivisions, and in 1999 the Library of Congress (LC) began identifying form subdivisions with the new code.

However, there are millions of older bibliographic records lacking the explicit form subdivision coding. Identifying form subdivisions retrospectively is not a simple task. An algorithmic method was developed to identify form subdivisions coded, as general subdivisions. The algorithm was used to identify 2,563 unique form subdivisions or combinations of form subdivisions in OCLC’s WorldCat. The algorithm proved to be highly accurate with an error rate estimated to be less than 0.1%. The observed usage of the form subdivisions was highly skewed with the 100 most used form subdivisions or combinations of subdivisions accounting for 90% of the assignments.