Information on differentia
Differentiae in the Klosterneuburg manuscripts are written in the margins of the manuscripts, but staff lines (usually just the F and/or C line) are extended into the margins to clarify the pitched content of each differentia. The original Cantus index for this manuscript coded the differentiae with a two-digit system: an upper-case letter to indicate the final pitch of the differentia within each mode followed by a sequentially-ordered numeral. The coding system was consistent throughout the eight Klosterneuburg manuscripts.
Lacoste, Debra. Inventory of Klosterneuburg, Augustiner-Chorherrenstift - Bibliothek, 1012. 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-). Lacoste, Debra. “The Earliest Klosterneuburg Antiphoners.” Ph.D. dissertation, The University of Western Ontario, 1999.
Images: Klosterneuburg, Augustinian Monastery, Cod. 1012, Handschriftensammlungen, Manuscripta, Austrian National Library