Diatonic scale are major scales (those with a major third/triad: Ionian, Lydian, and Mixolydian), three are minor (those with a minor third/triad: Dorian, Phrygian, and Aeolian). To these may be added the seventh diatonic scale, with a diminished fifth above the reference note, the Locrian scale. These could be transposed not only to include one flat in the signature (as described by Glarean), but to all twelve notes of the chromatic scale, resulting in a total of eighty-four diatonic scales. The modern musical keyboard originated as a diatonic keyboard with only white keys. The black keys were progressively added for several purposes:
Yo scale A - B. This is illustrated below. The Ryūkyū scale appears to be derived from the yo scale with pitches raised. More recent theory emphasizes that it is more useful in interpreting Japanese melody to view scales on the basis of "nuclear tones" located a fourth apart and containing notes between them, as in the "min'yō" scale used in folk music, and whose pitches are equivalent to the second mode of the "yo" scale: Yo scale The "yo" scale, which does not contain minor notes, according to a traditional theory is a pentatonic scale used in much Japanese music including