The intellectual or artistic realization of a work in the form of alpha-numeric, musical, or choreographic notation, sound, etc., or any combination of such forms. For example: Work #1 Franz Schubert's Trout quintet * Expression #1 the composer's score * Expression #2 sound issued from the performance by the Amadeus Quartet and Hephzibah Menuhin on piano * Expression #3 sound issued from the performance by the Cleveland Quartet and Yo-Yo Ma on the cello * . . . . The Music Ontology defines the following sub-concepts of a MusicalExpression, which should be used instead of MusicalExpression itself: Score (the result of an arrangement), Sound (produced during a performance), Signal. However, it is possible to stick to FRBR and bypass the worflow mechanism this ontology defines by using the core FRBR properties on such objects. But it is often better to use events to interconnect such expressions (allowing to go deeply into the production process - `this performer was playing this particular instrument at that particular time').