.
In the Diatonic genus we should have expected that the original characters would have been used for the tetrachords b c d e and e f g a; and that in other tetrachords the second note, being a semitone above the first, would have been represented by a reversed letter (gramma apestrammenon). In fact, however, the Diatonic Parhypatê and Tritê are written with the same character as the Enharmonic. That is to say, the tetrachord b c d e is not written
, but
: and d e♭ f g is not
, but
.