Chord sequence
Am7 D7 B♭m7 E♭7
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
Chords 1 to 2
Am7 D7
Chords 3 to 4
Bbm7 Eb7
Over Am7 · ♭ii7
Mode 6 of Blues
Over D7 · V7/vii
Over Bbm7 · ii7
Mode 2 of Major
Over Eb7 · V7
Mode 5 of Major