Chord sequence
Bm7♭5 B♭7 Amaj7
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 A major
Over Bm7b5 · iiø7
Mode 2 of Harmonic Minor
Over Bb7 · subV7
Mode 4 of Melodic Minor
Over Amaj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.