Decretum Gratiani is the more commonly known name given to the celebrated work Concordia discordantium canonum, a collection of canonical law sources made up by Gratianus, a Benedictine monk of Camaldoli, in the first half of the eleventh century (1140-1142 circa). This original collection was subsequently supplemented by a large number of compilationes and by the most recent canonical rules, the so called extravagantes, which were afterwards added to. It is here dealt with one of the Canonical Law fundamentals, present in the inventories of various canons of Aquileia, Cividale and Udine. This codex of the Decretum, which exhibits the ordinary gloss as well, was copied at Bologna around the third decade of the thirteenth century and, after some handovers among Bologna students, finally purchased by a canon of Cividale, Marsilius (1244-1256 circa), who was also student at Bologna and eventually left it to the chapter of Cividale. In 1256 it was lent to the patriarch of Aquileia Gregorio di Montelongo who used it in the exertion of his own duties and then gave it back upon his death in 1269. In 1447 the Chapter decided to chain it up in the chapter hall, as it is evidenced by the corresponding resolution text copied on the flyleaves.