A double tonic is a chord progression, melodic motion, or shift of level consisting of a, "regular back-and-forth motion," in melody similar to Bruno Nettl's pendulum type though it uses small intervals, most often a whole tone though may be almost a semitone to a minor third (see pendular thirds). It is extremely common in African music ("Mkwaze mmodzi"), Asian music, and European music, including: Am|G|Am-G|Am|| They are also often varied through a binary scheme ending on the dominant then tonic, as in: Am|G|Am|E|| Am|G|Am-G|Am|| or, Am|G|Am|E|| Am|G|Am-E|Am||