Köln (Cologne), Erzbischöfliche Diözesan- und Dombibliothek, 215

In the late thirteenth century, a tonary (ff. 209v-212r) was added to this manuscript in diastematic neumes, although the rest of the manuscript is written in adiastematic neumes and dates from the twelfth century. Throughout the manuscript, differentiae are indicated by tonary letters, but these tonary letters are not replicated in the thirteenth-century tonary, and there is no clear indication of how these two systems of differentiae identification correspond with each other. The differentiae included in the Differentiae Database are from the tonary.