The function symbol notation is the least used notational system in jazz. As the namesuggests, this notation specifies the harmonic function of individual chords and evencomplete chord progressions. It has the potential of being useful to notate specificbehaviors of chords that may not—at least, not on the surface level—indicate that theybelong to a particular functional family of chords. As such, function symbols enable theperception of harmonic progressions from a more structural perspective. Function symbolsindicate neither the architecture nor the specific scale degrees of chords. This style ofnotation is more conceptual than it is representative of a specific surface event. The termssurface level and structural level are used to describe musical events and the degree oftheir importance. “Structural” events occur beneath the musical “surface” and areresponsible for the overall tonal, harmonic, and melodic forces controlling the piece.Function symbols use three labels: T for tonic-type chords, PD for predominant-typechords, and D for dominant-type chords.