MARC and the Subject Approach 

The concept of MARC (Machine Readable Catalogue) has brought in a new era in the field of library and information services. MARC stimulated the development of library automation and information networks. Planning for MARC - I begun in 1966 and concluded in 1968. For forms of materials other than books, Library of Congress (LC) published formats for serials and maps in 1970, films in 1971 and manuscripts in 1973. Designing of MARC - II was based on the experiences gained during the evaluation of MARC - I format. The idea behind MARC - II was to develop one common format structure capable of containing bibliographic information for all forms of documents. Not all the information  in the MARC record is relevant to the subject of a document, but certain fields are likely to be more productive than others in providing a range of subject descriptions. Some fields are related specifically to notation/class number derived from different schemes of library classification, such as those of LCC, UDC, DDC and NLM; and others are related to alphabetical subject headings, such as those drawn from LCSH, PRECIS, and other alphabetical systems.