Chord sequence
B♭m7 E♭7 Am7 D7 A♭m7 D♭7 G♭maj7
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 Gb major
All the chords
ii-Vs falling by half steps: iii-VI, the ii-V a half step lower, then ii-V-I.
Over Bbm7 · iii7
Mode 6 of Major
Over Eb7 · V7/ii
Mode 6 of Blues
Over Am7 · ♭iii7
Mode 2 of Major
Over D7 · ♭VI7
Mode 4 of Melodic Minor
Over Abm7 · ii7
Over Db7 · V7
Mode 5 of Major
Over Gbmaj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.