Heptatonic scale are considered subsets of a twelve-pitch scale roughly analogous to the Western chromatic scale. The first and fifth melakarta tones, corresponding to the first and eighth chromatic tones, are invariable in inflection, and the fourth melakarta tone, corresponding to the sixth or seventh chromatic tone, is allowed one of two inflections only, a natural ("shuddah") position and a raised ("tivra") position. The second and third melakarta tones 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
Chromatic circle major (Ionian mode), minor (Aeolian mode) and Mixolydian - include these pitches. Symmetric scales have simple representations in this scheme. More exotic scales - such as the pentatonic, blues and octatonic - can also be drawn and related to the common scales. A more complete list of musical scales and modes In previous sections we saw how various overlays (scale degrees, semi-tone numbering, notes) can be used to notate the circumference of the constellation. Various other overlays can be laid around the constellation. For example: Note that once a pitch constellation has been determined, any number of overlays (notes, solfège,