Information on differentia
Differentiae are written after each antiphon and accompanied by the text "Euouae" or the textual incipit for the psalm. In the original Cantus index, differentiae were identified by a two-digit system, with a letter to indicate the last pitch of the differentia and a number to distinguish between differentiae within the same mode that shared the same last pitch.
Dietz, Judith, Jennifer Bain, and Meredith Evans. Inventory of Halifax (Canada), St. Mary’s University - Patrick Power Library, M2149.L4 1554 [Salzinnes Antiphonal]. Edited by Debra Lacoste. Additional fields added or edited by Alessandra Ignesti, Maria Murphy, Clare Neil, and Barbara Swanson. 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: Salzinnes, CDN-Hsmu M2149.L4, Cantus Ultimus