Chord sequence
A♭maj7 Fm7 B♭m7 A7
In every key
Four-note rootless voicings in their two forms, with the 3rd or the 7th on the bottom, played over the root.
Heard in Ab major
Over Abmaj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.
Over Fm7 · vi7
Mode 6 of Major
Over Bbm7 · ii7
Mode 2 of Major
Over A7 · subV7
Mode 4 of Melodic Minor