Any vocabulary, controlled or uncontrolled used for indexing ,along with the rules of usage.Is much more than a list of index terms that are acceptable to users.
Helps users discriminate between terms and reduces an ambiguity in the language. To assist both indexers and searchers in using and manipulating the system.
Assigned term Derived term
An indexer must assign terms or descriptors on the basis of subjective interpretation of the concepts implied in the documents. The indexer determine the subject matter of the document at hand. Assigned descriptors from a controlled vocabulary, which identifies concepts expressed by the documents author.
All the descriptors are taken from the text itself. Sometimes called natural language or free text indexing.
Is a related group of words or phrases adopted by a particular group of people to be used in an indexing activity. Formal lists of the words in the controlled vocabulary.
Evolutionary vocabulary- consists of raw material supplied by indexers.- Which is edited or planned after the fact. Enumerated vocabulary- Is generated as the result of a special study or inquiry and a consensus of experts who predetermine what the vocabulary should be for an area of knowledge.
Show vertical arrangements of words within classes. Indicate synonymous relationships, near synonymous relationships and related word groups.
Specific language, with words, relationships of words and its own grammatical rules for usage. It is a controlled , collected subset of natural language.
Consistency in indexing and searching. The control of synonyms, although it has many other functions such as related words, more specific words and broader words.