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As a descriptor ( plural descriptors ) or keyword (plural Tags ) one calls usually given names that the content description of an object can be selected. The assignment of descriptors is also referred to as keywording (in Austria keywording ) or indexing . In contrast to key words - important words that occur in a text - key words mostly come from a controlled vocabulary in which it is determined which words should be used for which subject matter. Examples of such vocabularies are authority files and thesauri . The allocation of descriptors is part of the indexing of the content of documents, for example in libraries .

The term descriptor was introduced in the context of information recovery around the early 1950s by the American mathematician Calvin Mooers .

Types of descriptors

Some documentation systems contain so-called non-descriptors , which should expressly not be used for keywording.

A general descriptor is a descriptor which on its own usually has no informative value, e.g. B. "Cost" ( of what? For whom? Which taste? ).

If individual descriptors are used for certain people, we speak of personal keywords as opposed to subject keywords.

Descriptors from an artificially based documentation language (e.g. universal decimal classification key ) are called notation .

With free keywording (also known as " tagging "), descriptors are not selected from a given pool, but are freely assigned. The disadvantage of free subject indexing is the lack of control. The indexing work is partly shifted to the searcher, who has to look for all different spellings, different cases (e.g. singular-plural), synonyms etc. and exclude homonyms .

Keyword vs. classification

The contents of objects such as articles or monographs can be described by assigning keywords to the main or partial content (s) of that object (this process is called "keywords", indexing, black and Austrian "keywords") or by assigning individual classes of a certain classification for the main or partial content of the object (this process is called "classifying" or "classifying"). The classification indicates the subject or subject area within which the content is dealt with, which the keywords indicate.

See also