Constant structure
Appearance
In jazz, a constant structure is a chord progression consisting of three or more chords of the same type or quality[1]. Popularized by pianists Bill Evans and Herbie Hancock, the combination of functional and non-functional chords provides cohesiveness while producing a free and shifting tonal center[1].
For example, the progression CM7-DM7-EM7-F♯M7 contains only major seventh chords, none of which are diatonic to the key of C major except the first.