Information on differentia
The differentiae were originally indexed by a two-character code: an upper-case letter denoting the last note of the differentia and a sequentially-ordered number to distinguish between differentiae of the same mode that ended on the same note. The differentiae are included in the manuscript at the end of each antiphon and are accompanied by the standard "Euouae" or psalm incipit text.
Mitchell, Andrew. Inventory of Augsburg Antiphoner (1495); London, British Library, printed book IB. 6753. In Cantus: A Database for Latin Ecclesiastical Chant. Directed by Debra Lacoste (2011-), Terence Bailey (1997-2010), and Ruth Steiner (1987-1996). Web developer, Jan Kolácek (2011-).
Microfilm with manuscript images available from the British Museum (IB 6753, Order SCH 869).