Information on differentia
Differentiae are written on staff-lines at the end of each antiphon, accompanied by "Euouae" or the textual incipit of the psalm. In the original Cantus index, differentiae were ascribed a two-digit code, with the number distinguishing between differentiae in a mode, and a lower-case letter distinguishing variations of similar differentiae (e.g., 1a, 1b, 2a, 2b, etc.). The manuscript also includes a tonary (ff. 285v-286v).
Downey, Charles, and Joseph Metzinger. Inventory of Vorau, Stiftsbibliothek, 287 (olim XXIX). 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: Vorau-Salzburg (OSA)