Role of a Thesaurus in Indexing and Searching
The thesaurus contributes to consistency in indexing between indexers and reduces incorrect term assignments to a great extent because of the provision of the term definition or scope note. This is particularly true if descriptors, which are some what related, are carefully distinguished by scope notes.
Thesaurus plays the following two roles
a) prescriptive role. It prescribes as to what term should be assigned. The 'use' reference is a prescriptive indicator.
b) suggestive role. It suggests terms to be considered instead of, or in addition to etc. The RT (and to a certain extent the BT and NT) are suggestive indicators.