At one time, this manuscript was part of a larger book. (See the earlier layer of foliation on some folios: f. 31r which was at one time f. lxxxv, for example.) F. 12 is out of place; it belongs before the present f. 1.
Many of the differentiae in this manuscript have been redrawn or erased. The differentiae of each mode have been numbered with a two-digit system: an upper-case letter indicating the final pitch of the differentia and a sequentially ordered numeral.
Chants not found in CAO have been assigned arbitrary numbers beginning with “our.”