Chord sequence
Dmaj7 E♭dim7 Em7 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 D major
All the chords
The I-VI-ii-V with a diminished 7th chord on #I in place of VI7, so the bass rises by half steps from I to ii.
Over Dmaj7 · Imaj7
The major scale and its modes are the most commonly used scales in western music.
Over Ebdim7 · ♭ii°7
Mode 7 of Harmonic Minor
Over Em7 · ii7
Mode 2 of Major
Over A7 · V7
Mode 5 of Major