Library of Congress Classification Numbers: Issues of Consistency and Their Implications for Union Catalogs.

This study examined Library of Congress Classification (LCC)-based class numbers assigned to a representative sample of 200 titles in 52 American library systems to determine the level of consistency within and across those systems. The results showed that under the condition that a library system has a title, the probability of that title having the same LCC-based class number across library systems is greater than 85 percent. An examination of 121 titles displaying variations in class numbers among library systems showed certain titles (for example, multi-foci titles, titles in series, bibliographies, and fiction) lend themselves to alternate class numbers. Others were assigned variant numbers either due to latitude in the schedules or for reasons that cannot be pinpointed. With increasing dependence on copy cataloging, the size of such variations may continue to decrease. As the preferred class number with its alternates represents a title more fully than just the preferred class number, this paper argues for continued use of alternates by library systems and for finding a method to link alternate class numbers to preferred class numbers for enriched subject access through local and union catalogs. [ABSTRACT FROM AUTHOR]