can be picked from the 4 chromatic tones (second through fifth), and similarly for the sixth and seventh. Thus the number of possible forms is equal to twice the square of the number of ways a two-membered subset can be extracted from a four-membered set: Thaat Hindustani heptatonic theory additionally stipulates that the second, third, sixth and seventh degrees of heptatonic scale forms (septak) are also allowed only two inflections each, in this case, one natural position, and one lowered (komal) position. Arithmetically this produces 25, or thirty-two, possibilities, but Hindustani theory, in contradistinction to Carnatic theory, excludes scale forms not commonly used. Chinese Gongche notation Gongche notation heptatonic scale gives a do, re, mi, (between fa and fa), sol, la, (between ti and ti) heptatonic scale. See also Diatonic and chromatic Modes of the ancohemitonic heptatonic scales and the key signature system References