Instructional videos -- See Instructional films This heading is used as a topical heading for works about films designed to impart skills or techniques to general audiences, typically in a "how-to" manner. Works about films intended for teaching and informational purposes, especially those made for classroom viewing, are entered under Educational films. When used as topical headings they are subdivided by the appropriate geographic, topical, and/or form subdivisions.
Instructors -- See Teachers Here are entered works on persons whose occupation it is to instruct. Works on persons who are specialists in the field of education or who are authorities on educational problems, theories, and methods are entered under Educators.
Instrument approach systems -- See Instrument landing systems Here are entered general works on systems of landing aeroplanes by instruments when visibility is low or practically nonexistent, and also works on the specific system known as ILS (instrument landing system). Works on other individual systems are entered under specific headings, e.g. Ground controlled approach.
Instrumental ensembles -- See Also Chamber music Here are entered miscellaneous collections of chamber music for various combinations of two through nine solo instruments or voices with instrumental accompaniment.Collections for the same combination of solo performers, and individual works, are entered under headings specifying the medium of performance, e.g. Bassoon music (Bassoons (2)); Duets (Unspecified instruments (2)); String quartets; Suites (Bassoon, clarinet, trombone, violin); Vocal quartets with instrumental ensemble.