Merits and Deficiencies 

The strongest aspect of LCSH is that it represents subject headings of a national library, one of the most richest of national libraries of the world. The administrative and managerial  machinery LC  has, made it possible for LCSH stand out as an undisputed leader almost on all aspects of library development. As has been already stated in this Unit, LCSH is also used as indexing vocabulary in a  number of published bibliographies. In addition to the printed version, LCSH is now available on microfiche, revised quarterly; on CD-ROM, revised quarterly; and online through the LC Internet node. A number of Bibliographic Utilities allow searching by LCSH. The prominent examples  are the Research Libraries Information Network (RLIN) and Washington Library  Network's own online catalogue with access by subject, often with sophisticated search options; most of these libraries use LCSH for subject cataloguing. 

With all these strengths and reputation, the Library of Congress has yet to publish a statement of principles  for its subject cataloguing system.  Without a proper theoretical foundation, it  has become a mammoth tool rather becoming difficult to use: The principles that underline the system, have to be inverted from practice and policy statements. 

Very often  LCSH is criticised on grounds  of its outdated terminology, illogical syntax and general inefficiency for precise subject retrieval. Its limitations are that it would meet the subject cataloguing requirements only for macrodocuments. Its use as a bibliographic list, therefore, cannot be extended to index microdocuments. 

Conscious of all these drawbacks,  more intensive  efforts are underway at LC to modernise its subject heading system, and systematise the existing tool. Many of its new features recently introduced represent steps in this direction. For the foreseeable future, LCSH gives every sign of retaining its vitality and  prominence for  subject access to library collection.