The fragment consists of a single page, preserved in a modern folder (assigned the shelfmark Librone 3bis in November 2020) together with Fragment 1. Only the lower half of the original folio is extant. Similarly to Fragment 1, it was apparently restored during the 1950s and then forgotten in the Archive of the Veneranda Fabbrica until March 2019. No data have been retrieved about its original position and the circumstances leading to its present state. The recto contains the conclusion of the Altus (text only) and the full Bassus of the secunda pars of a motet by Compère. The verso is completely blank (no ruling). Based on the size, mise en page (with presumably 10 staves) and scribal hand, it might have formerly belonged to Librone 3.