Index from a onetime musical manuscript repurposed as the a rear flyleaf for the Cartulaire de l'archevêché de Besançon (Cartulary of the Archbishopric of Besançon). Although this source contains no actual music, the index on p. 117 preserves 57 incipits, the majority of which are concordant with motets known from Montpellier, Bamberg, Clayette, Torino Vari 42, and other late 13th century sources. Three pairs of neighboring incipits share a number, suggesting the numbering is indicative of the folio or opening where the motets appeared.
Not in RISM or CCMS but known since Paul Meyer's discovery in 1898.