Terminological databases using the conceptual approach to the structuring of content resemble the form of a thesaurus more than that of the conventional, alphabetically ordered dictionary. It is in fact accepted that the most appropri
ate form of classifying and presenting terms is via a methodology which owes much to the principles of thesaurus construction.
The advantages and relevance of a thesaural structure to terminology were recognised early by terminologists because it could represent relationships between concepts in as much detail as necessary, in the same way as docu
mentation thesauri do between document descriptors. Wüster's dictionary T h e Machine Tool' (1968) can be seen as a forerunner of the terminological thesaurus in that there is a conceptual organisation of terms, based on the Universal Decimal Classification.
Historically, thesauri have evolved into three specific forms as appropriate to their separate and distinct functions, viz.
- general language thesauri, i.e. dictionaries of synonyms, analogue expres
sions, ideas suggested by words;
- documentation thesauri for indexing and retrieval of documents;
- terminological thesauri which combine feature of the other two.
The function of a documentation thesaurus is normally perceived as a ter
minological control device used in translating from the natural language of documents, indexes or users' queries into a restricted language which permits more efficient indexing and retrieval. By form a documentation thesaurus is a controlled and dynamic vocabulary of semantically and generically related terms which covers a specific domain of knowledge. This vocabulary consists of selected terms (known as document descriptors) and declared relationships between them such as 'generic broad term', 'narrow term partitive' or 'related term'. The control is exercised by two references: UF (use for) indicates a preferred term or descriptor, and USE indicates a non-preferred term or non- descriptor.
Thesauri usually have two parts: an alphabetical list and a systematic dis
play.
The alphabetical list may add information on the entries such as scope notes and include a list of related terms up to one hierarchical level (such as 'narrow term' and 'non-preferred term'). Consulting the alphabetical list, the user is led, if need be, to more or less specific terms or possibly more suitable terms of the same level of specificity.
The systematic subject display is the main part of the thesaurus since it provides most of the definitional and relational information in the form of a hierarchical structure. The user may be led to the location of the desired term by an 'address code' given in the alphabetical index. Terms are grouped by subject area and arranged according to their meanings and relationships.
Scope notes and reciprocal references to equivalent and related terms may be displayed and relationships to broader and narrower terms are indicated by the position of a term within a hierarchy and its level of indentation. This classification is often refined by using facets in one form or another which serve to indicate the logical basis for subdividing a category.
A terminological thesaurus is more than a simple dictionary, glossary or vocabulary as it aims at a coherent systematic representation of the knowledge structure of a subject field. Such a tool has the advantage of showing the full extension of a term and its place within the broader conceptual environ
ment of the overall knowledge structure it belongs to, thus complementing the definition which can, in this way, concentrate on the intension of concepts.
Since the conceptual structure is the basis for any description of the lexicon of
Retrieval of Terminology 205 special languages, a dictionary or glossary may be created on the basis of the terminological thesaurus, but never vice versa.
Whether or not one can accurately represent the conceptual structure of special subject fields and precisely situate concepts in a terminological the
saurus is a matter of debate. Decisions that have to be made during compila
tion will often be of a subjective nature and each terminologist may have a different view of the knowledge structure. As yet, there appears to be little in the way of concrete and universally agreed-upon rules and conventions for constructing terminological thesauri and for establishing relationships and hierarchies. This may explain the fact that there are relatively few actual examples of systematically structured dictionaries.
Amongst those glossaries and dictionaries which have adopted some kind of conceptual structure, very few can be described as 'terminological the
saurus' in the full sense of the concept. Many systematic structures consist of groupings and/or hierarchies of terms based on very arbitrary, questionable and often opaque criteria. This applies even to some of the British Standards Institution glossaries, e.g. BS 5408:1976, Glossary of Documentation Terms.
This document incorporates a systematic index which, however, lacks consist
ency and places many concepts in broad, over-generalised categories.
Nevertheless, a dictionary incorporating some indication of interrelation
ships, provided that this information is neither misleading nor redundant, is a step in the right direction and the terminological thesaurus is, arguably, the most effective means of capturing these relationships usefully.
Chapter Eight