Octatonic scale scale" . The twelve tones of the chromatic scale are covered by three disjoint diminished seventh chords. The notes from two such seventh-chords combination form an octatonic collection. Because there are three ways to select two from three, there are three octatonic scales in the twelve-tone system. Each octatonic scale has exactly two modes: the first begins its ascent with a whole step, while the second begins its ascent with a half step (semitone). These modes are sometimes referred to as the "whole step/half-step diminished scale" and the "half-step/whole step diminished scale", respectively. Each of the three distinct scales can
Transposition (music) Thus the set ("A") consisting of 0–1–2 transposed by 5 semitones is 5–6–7 (T("A")) since , , and . There are two different kinds of transposition, depending on whether one is measuring intervals according to the chromatic scale or some other scale. In chromatic transposition one shifts every pitch in a collection of notes by a fixed number of semitones. For instance, if one transposes the pitches C–E–G upwards by four semitones, one obtains the pitches E–G–B. In scalar transposition one shifts every pitch in a collection by a fixed number of scale steps relative to some scale. For example,