FACETED CLASSIFICATION IN THE ART AND ARCHITECTURE THESAURUS

Most controlled vocabularies currently in existence arise as part of the indexing or cataloging process within a particular institution. They exist in a variety of forms ranging from sim ple term lists to elaborate subject heading systems. Because most controlled vocabularies are created internally for a par ticular medium and subject concentration they reflect the content of the local collection and are designed for use with a particular resource, such as slides or books. The Art and Architecture Thesaurus is, in a sense, different from existing controlled vocabularies because it is developing a relatively exhaustive framework of terminology in an a priori fashion. It is not tied to any one type of indexing or cataloging situation. Using existing subject heading lists and over 2,000 other sources, such as subject-specific dictionaries and mono graphs, the AAT has thus far identified, defined, and concep tually arranged over 35,000 terms, or descriptors, about one third of which are synonyms and variant spellings, or lead-in vocabulary. The terminology is initially gathered and verified by the AAT staff and then undergoes a review process in which scholars and other experts in particular fields critique the choice of terms and the relationships that have been established between them. Terms in the AAT are arranged into broad conceptual units called facets as shown in Figure 1. The AAT defines a facet as a mutually exclusive, fundamental class of terms whose members share characteristics that distinguish them from the members of other classes. The faceted approach to index ing language and indexing systems was first introduced by Shiyali Ramamrita Ranganathan in Colon Classification, first published in 1933.1 In this scheme, knowledge as represented by language is divided into five fundamental classes: Person ality (P), Matter (M), Energy (E), Space (S), and Time (T). These categories may be applied continually throughout all levels of a particular topic. For example, in this scheme "Art" would be in the Personality facet, but the field of Art could be broken down further into facets derived from PMEST. For example, "Paintings" would belong the to the Matter facet.