OCLC was also running WorldCat - the name of the OCLC Online Union Catalog - which is a merged electronic catalog of library catalogs around the world, and the world's largest bibliographic database with its 38 million records (in early 1998) in 400 languages (with transliteration for non-Roman languages), and an annual increase of 2 million records.
WorldCat stemmed from a concept which is the same for all union catalogs: earn time to avoid the cataloguing of the same document by many catalogers worldwide. When they are about to catalog a publication, the catalogers of the member libraries search the OCLC catalog. If they find the record, they copy it in their own catalog and add some local information. If they don't find the record, they create it in the OCLC catalog, and this new record is immediately available to all the catalogers of the member libraries worldwide.
Unlike RLIN, another main union catalog that accepts several records for the same document (please see below), the OCLC Online Union Catalog accepts only one record per document, and asks its members not to create duplicate records for documents that were already cataloged. The records are created in USMARC format (MARC: Machine Readable Catalog) according to the Anglo-American Cataloguing Rules, 2nd version (AACR2).
What is the history of OCLC? "In 1967, the presidents of the colleges and universities in the state of Ohio founded the Ohio College Library Center (OCLC) to develop a computerized system in which the libraries of Ohio academic institutions could share resources and reduce costs. OCLC's first offices were in the Main Library on the campus of the Ohio State University (OSU), and its first computer room was housed in the OSU Research Center. It was from these academic roots that Frederick G. Kilgour, OCLC's first president, oversaw the growth of OCLC from a regional computer system for 54 Ohio colleges into an international network. In 1977, the Ohio members of OCLC adopted changes in the governance structure that enabled libraries outside Ohio to become members and participate in the election of the Board of Trustees; the Ohio College Library Center became OCLC, Inc. In 1981, the legal name of the corporation became OCLC Online Computer Library Center, Inc. Today, OCLC serves more than 27,000 libraries of all types in the US and 64 other countries and territories." (excerpt from the 1998 website)
In early 1998, WorldCat had 38 million records - with one record per document. RLIN (Research Libraries Information Network) had 88 million records - with several records per document.
RLIN was run by the Research Libraries Group (RLG). The central RLIN database was a union catalog of 88 million items held in main libraries belonging to RLG member institutions, including research and specialized libraries, like law, technical, and corporate libraries.
RLIN included:
(1) records that described works cataloged by the Library of Congress, the National Library of Medicine, the US Government Printing Office, CONSER (Conversion of Serials Project), the British Library, the British National Bibliography, the National Union Catalog of Manuscript Collections, and RLG members and users;
(2) nearly all the books cataloged since 1968 and rapidly expanding coverage for older materials;
(3) information about non-book materials ranging from musical scores, films, videos, serials, maps, and recordings, to archival collections and machine-readable data files;