Information on differentia
In the original Cantus index for this manuscript, differentiae were identified with a two-digit system, whereby the first character indicates the last note of each differentia and an arbitrarily-assigned number distinguishes between differentiae of the same mode that end on the same note.
Mitchell, Andrew. Inventory of Rouen, Bibliothèque municipale, 248 (olim A. 339). Edited by Debra Lacoste. 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-).
Differentiae indexed in consultation with a microfilm facsimile of the manuscript.