The Subject Headings Manual and the Library of Congress Subject Headings provide guidance for the choice and formulation of subject headings.  H 2230 deals specifically with visual materials.

Subject headings serve as a primary means of access to materials of all kinds that are described in collection-level records.  All types of subject headings may be assigned.  They should be as specific as the collection warrants.  The applicability of terms referring to only portions of the collections may be specified.

650 #0 $a Kathak (Dance) $3 videocassette only

There is no limit to the number of subject headings that may be assigned, but, in the cases of collections constructed for reasons of economy in processing, a reasonable limitation should be observed.

For guidance on applying genre and form terms, a standard list, such as The Moving Image Genre-Form Guide or Moving Image Materials: Genre Terms, may be used.

See also:

Appendix C:  Collection-Level Cataloging