Information on differentia
The original Cantus index for this manuscript identified differentiae using a two-digit system, where an upper-case letter indicated the last pitch and a number distinguished between differentiae of the same mode that share a common last pitch. Differentiae that vary only in terms of repeated notes, the addition of liquescents, or neumation, are distinguished by a lower-case suffix in the "Extra" field of the index.
Mitchell, Andrew. Inventory of Fribourg, Bibliothèque des Cordeliers, 2. 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: Fribourg/Freibourg, Couvent des Cordeliers/Franziskanerkloster, Ms. 2, ff. 1-245