Controlled Indexing Language
In the foregoing paragraphs we have discussed the concept of an indexing language as also, the categories into which it falls. In the process, we have learnt the meaning of natural indexing and free indexing languages. Let us now learn some facts regarding controlled indexing languages and their use in subject cataloguing and indexing.
Control is necessary in respect of terms used as subject identifiers in a catalogue or index, because of the variety of natural languages. Such control may involve barring of certain terms from use as headings or access points in a library catalogue or an index. The term which are to be used are specified and the synonyms recognised and as far as possible are eliminated. Preferred word forms are noted. The list of terms, thus, prepared constitutes what is called controlled indexing language. One of the methods by which such a language is formed, is to list or store the acceptable terms in a vocabulary. Such lists contain specific decisions relating to the preferred words, and also decisions regarding the form of words to be used; for example, singular or plural, nouns or adjectives. There are mainly two types of controlled indexing languages in verbal plane. They are: subject heading lists and thesauri. These two types of controlled indexing languages have the following functions:
- to control the terminology used in subject catalogues and indexes; and
- to control the display of relationships in catalogues and indexes.
Subject heading lists are lists of index terms normally arranged in alphabetical order, which can be used to determine the terms to be used in a catalogue for describing subjects (i.e., as subject headings) by cataloguers: These lists attempt to solve some of the problems concerning alphabetical subject approach. They serve as guides to the cataloguer and aid him in the task of subject cataloguing. The basic functions of a subject headings list may be stated in the following terms:
- The list records terms which shall be used in a catalogue or database, and also indicates the form in which they shall be shown. It acts as an authority list for index terms and their form.
- The list makes recommendations about the use of references for the display of relationships in a catalogue in order to guide the users to distinguish associated terms.
'Sear's List of Subject Headings and 'Library of Congress List of Subject Headings' are examples of popular list of subject headings. These two lists have been the basis for discussion in respect of alphabetical subject catalogues or in other words, for the theory and practice of subject cataloguing.