Liber Extra
Sometimes also the name "regulars" was applied to the canons regular to distinguish them from monks. Thus the collection of Gratian (about 1139) speaks of canons regular, who make canonical profession, and live in a regular canonicate, in opposition to monks who wear the monastic habit, and live in a monastery. But the "Decretals of Gregory IX", promulgated 5 September 1234, use the word "regularis" in a more general sense, in book III, ch. xxxi, which is entitled "De regularibus et transeuntibus ad religionem". However in ch. xxxv "De statu monachorum et canonicorum regularium" the distinction returns, disappearing in the corresponding book and chapter of the "Decretals of Boniface VIII" (3 March 1298), which is entitled merely "De statu regularium" and reappearing in the collection of Clementines (25 Oct., 1317) but with the conjunction vel, which indicates the resemblance between them.