Template:Controlled vocabulary

alphabetic list of terms defined as permissible for a specific indexing project. An example would be Library of Congress Subject Headings, a compendium of documents used by the U. S. Library of Congress to define the terms that may be used to index its collections. It has been adopted as the governing work for indexing the collections of many other libraries of general works. Specialized collections (e.g. National Library of Medicine) often develop their own more specific controlled vocabulary.