Genus (music) the other hand, also has twelve pitches to the octave, but the semitones are all of the same size. In contrast, the ancient Greek chromatic scale had seven tones to the octave (assuming alternating conjunct and disjunct tetrachords), and had incomposite minor thirds as well as semitones and whole tones. The (Dorian) scale generated from the chromatic genus is composed of two chromatic tetrachords: whereas in modern music theory, a chromatic scale is: The number and nature of the shades of the chromatic genus vary amongst the Greek theorists. The major division is between the Aristoxenians and the Pythagoreans. Aristoxenus
Octave standard 88-key piano keyboard, while the C an octave higher is C. The notation "8" or "8" is sometimes seen in sheet music, meaning "play this an octave higher than written" ("all' ottava": "at the octave" or "all' 8"). "8" or "8" stands for "ottava", the Italian word for octave (or "eighth"); the octave above may be specified as "ottava alta" or "ottava sopra"). Sometimes "8" is used to tell the musician to play a passage an octave "lower" (when placed under rather than over the staff), though the similar notation "8" ("ottava bassa" or "ottava sotto") is also used.