ABSTRACT
An indexing language is out of date as soon as, if not before, it is published, so that any ‘live’ thesaurus must be updated regularly. Thesauri with specific vocabularies applied in systems using depth indexing tend to require updating more frequently than those confined to the use of more static, broader concepts. As would be expected, the need for modification increases, whatever the nature of the vocabulary or depth of indexing, as the number of documents that are indexed increases. The thesaurus grows most rapidly in the early stages of database development and levels off subsequently. At a later date, a further burst of growth may occur if the subject coverage of the database is extended.
