Liber Extra
The term Extravagantes (from the Latin "extra", outside; "vagari", to wander) is applied to the canon law of the Roman Catholic Church, to designate some papal decretals not contained in certain canonical collections which possess a special authority. More precisely, they are not found in Gratian's "Decretum" or the three official collections of the "Corpus Juris Canonici" (the "Decretals of Gregory IX", the "Sixth Book of the Decretals", and the "Clementines").