Discovered by Francesco Carta and first described in 1939 by Angelo Monteverdi, m is a bifolium (cut into 2 almost perfect halves) belonging to the 6th quire (quires are numbered in red ink on the top margin) of a late 13th Century Troubadour Chansonnier probably copied in Western Tuscany.

The fragment was reused to reinforce the binding of a 16th century printed book (Consiliorum siue controuersiarum forensium centuria prima Authore Camillo Borrello Oliuetano Iurisconsulto, Venetiis, apud Ioannem Guerilium, 1598) which was to be donated from the count Bartolomeo Arese to the Senate of Milan's library. Detached in the early 20th century, it is currently lost. 

It contains some poems by Peire d'Alvernha.