Composing in Real Time: Jazz Performances as “Works” in the FRBR Model

In Functional Requirements for Bibliographic Records (FRBR) and Functional Requirements for Authority Data (FRAD), realization of a musical work through performance is unambiguously included as a type of expression when it involves music in the Western canon. There is room for interpretation, however, as to whether an improvisation in jazz or rock constitutes an expression, or a new work with each performance. Multiple expressions, particularly transcriptions, and related works suggest the potential usefulness of treating a jazz performance as a work. This article examines the question of boundaries between one work and another, and illustrates ways that the FRBR model might be applied to cataloging improvisations.