ABSTRACT
This chapter provides the idea of pre-coordination and its application in subject headings, where the approach is predominantly verbal. Indexing system is one which, like Library of Congress Subject Headings (LCSH), sets out to create compound headings - i.e., headings which may contain two or more elements or facets. Traditionally, two forms of manually searched index have used pre-coordination: dictionary and classified indexes. The subdivision of headings is LCSH principal advance on Cutter, and the pre-coordination they provide greatly increases the precision of headings. Subdivisions are introduced by a hyphen. However, irregularities in the structure of Dewey Decimal Classification made it unsuitable for the machine generation of subject index entries, and the lack of specificity of a classification whose primary purpose was shelf arrangement was held to be inimical to good indexing practice. Effectively, what was to be devised was an articulated subject indexing system having a controlled vocabulary.
