canon, in Christianity, in the Roman Catholic Church, decrees of church councils are usually called canons; since the Council of Trent the expression has been especially reserved to dogmatic pronouncements of ecumenical councils. The body of ratified conciliar canons is a large part of the legislation of canon law. The Eucharistic central, mainly invariable part of the Mass is the canon. The term is also applied in the Western Church to certain types of priests. There are canons regular, priests living in community under a rule but not cloistered like monks; the Augustinian, or Austin, canons and the Premonstratensians are the best known of these. The priests attached to a cathedral or large church are sometimes organized into a group, or college, and called canons secular; a church having such a group is a collegiate church. A canon is also an official list, as in canonization, i.e., enrollment among the saints, and of the names of books of the Bible accepted by the church (see Old Testament; New Testament; Apocrypha; Pseudepigrapha). Cathedral canons often have diocesan charges or pastoral duties apart from the cathedral. Canons of the Church of England are mostly cathedral canons.