A list of terms that have been enumerated explicitly. This list is controlled by and is available from a controlled vocabulary registration authority. All terms in a controlled vocabulary must have an unambiguous, non-redundant definition. (ANSI/NISO Z39.19-2005)

National Information Standards Organization. (2005). Guidelines for the construction, format, and management of monolingual controlled vocabularies (ANSI/NISO Z39.19-2005). Bethesda, MD: NISO Press.