Prove it — just do the practice exercise.

Dm11 Root Position

D: R
F: ♭3
A: 5
C: ♭7
E: 9
G: 11

The m11 extends m9 by the 11th:

• R – ♭3 – 5 – ♭7 – 9 – 11

6 notes! The 11th (= 4th) reinforces the modal, Dorian character.

Example: Dm11 = D + F + A + C + E + G