Information on differentia
In the original Cantus index for this manuscript, differentiae were assigned a two-digit code that identified the last note of each differentiae and used a number to distinguish between differentiae in the same mode that shared the same last note.
Boynton, Susan. Inventory of New York, Columbia University, Rare Book and Manuscript Library, Plimpton MS 041. In: Cantus Manuscript Database for Latin Ecclesiastical Chant: Inventories of Chant Sources. Directed by Debra Lacoste (2011-), Terence Bailey (1997-2010), and Ruth Steiner (1987-1996). Web developer, Jan Kolácek (2011-).
Images: Antiphonal, Plimpton MS 41, Rare Book & Manuscript Library, Columbia University