Heptatonic scale

A heptatonic scale is a musical scale that has seven pitches per octave. Examples include the major scale (or minor scale), (e.g., in C major: C D E F G A B C—and in the relative minor, A minor: A B C D E F G); the melodic minor scale, C D E♭ F G A B C ascending, C B♭ A♭ G F E♭ D C descending; the harmonic minor scale, C D E♭ F G A♭ B C; and a scale variously known as the Roman Byzantine, and Hungarian, scale, C D E♭ F♯ G A♭ B C. Indian Classical theory postulates seventy-two seven-tone scale types, whereas others postulate twelve or ten (depending on the theorist) seven-tone scale types collectively called thaat.