Controlled vocabularies organize knowledge for retrieval by mandating predefined, authorized terms selected by designers. They include preferred and variant terms within a defined scope or domain. The objectives are to promote consistent representation of subjects and facilitate comprehensive searching by linking semantically and systematically related terms. Controlled vocabularies can be verbal like subject headings lists, or coded using notations. Terms are selected through various methods including subject experts and literature surveys. Advantages include avoiding confusion through synonyms and bringing related terms together to make searching easier. Tools for vocabulary control include classification schemes, subject heading lists, and thesauri.

1. CONTROLLED VOCABULARY
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2. Introduction
It provide a way to organize knowledge for subsequent
retrieval. They are used in subject indexing schemes, subject
headings, thesaurs, taxonomies and other knowledge
organization systems. Controlled vocabulary schemes
mandate the use of predefined, authorized terms that have
been preselected by the designers of the schemes, in contrast
to natural language vocabularies, which have no such
restriction.
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3. Definition
A controlled vocabulary is an organized arrangement of
words and phrases used to index content and/or to
retrieve content through browsing or searching. It typically
includes preferred and variant terms and has a defined
scope or describes a specific domain.
OR
Use of selected terminology to avoid scattering of related
subjects under different words, synonyms , near
synonyms, used in the text.
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4. Objectives
Two major objectives are;
1. To promote the consistent representation of
subject matter by indexers and searchers
thereby avoiding the dispersion of related
materials.
2. to facilitate the conduct of a
comprehensive search on some topic by
linking together terms whose meaning are
related paradigmatically or systematically.
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5. Kinds of Controlled Vocabulary
 Verbal
Coded
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6. Verbal
It is a term selected to represent a
concept or topic, lists of subjects
headings i.e Sears list of subject heading
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7. Coded
It is the use of notation as being
representation for a subject list of
vocabulary is always formed . Coding of
these selected terms is the secondary
stage of control.
010 Bibliography
020 Library Science
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8. Methods of selecting terms for
controlled vocabulary
1. Indexer’s own knowledge of the subject
2. Consultation with subject experts
3. Published classification schemes or lists of subject
headings
4. Available indexing services on the subject
5. The most reliable of all is by literary Warrant: the initial
choice of terms based on a survey of the subject
literature
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9. Advantages of controlled
vocabulary
1. Avoids confusion by controlling synonyms or near
synonyms
2. Brings semantically related terms together
3. Much easier to search
4. Avoids many problems of false coordination or
incorrect terms relationship.
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10. Vocabulary Control Tools
1.Classification sachems
2.Subject heading list
3.Thesauri
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11. Classification Schemes
o Colon Classification System
o Universal Decimal Classification
o Dewey Decimal Classification
Etc.
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12. Subject Heading List
 Library of Congress Subject
Heading
 Sears’ List of Subject Heading
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13. Thesauri
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