PRE-COORDINATE INDEXING MODELS
You will recall from your study of the sub-section 14.5.2 of Unit 14 that the pre-coordinate index constitutes a collection of index entries in which concepts from documents are co-ordinated according to a plan using a linear sequence at the time the index headings are prepared. These concepts are then represented either by symbols (when using a scheme of classification) or words of the indexing language in use. The next step is to synthesize or to put the components in an order recommended by the rules of the language. This means that the concepts are pre-coordinated and the index file consisting of a collection of such pre-coordinated concepts that are available in the library's collection of documents. Those pre-coordinated indexes when arranged alphabetically are known as alphabetical subject indexes or alphabetical subject catalogues. When arranged according to a scheme of classification they are known as classified indexes or classified catalogues.
All pre-coordinate indexing models are based on classificatory principles such as, facet analysis and synthesis. The functions performed by a pre-coordinate indexing models are discussed below: