Use refers to a liturgy practiced in a particular geographic region or by a particular group of people. The rites of the Christian liturgy developed along regional lines beginning in the Early Christian period (producing, for example, Roman, Ambrosian, Gallican, and Mozarabic rites), although the Roman rite largely came to be regarded as the standard in the West. The texts of the Mass and the Divine Office and their ordering throughout the year varied in accordance with these rites, with celebrations relating to local saints being particularly variable. The inclusion of local saints in calendars and litanies can provide useful clues as to use. During the later Middle Ages, some uses were codified by cathedrals or major religious orders (such as the Sarum rite of Salisbury and the Paris rite) and consequently spread beyond their region of origin. In the sixteenth century, as part of the general spirit of Catholic reform, the Council of Trent (1545-63) abolished uses that were less than two hundred years old in favour of Roman use; in Protestant England, the Book of Common Prayer (1549) mandated the observation of one use throughout the realm. In addition to a consideration of regional saints, use can be established by comparing certain elements of the text, such as the Psalm antiphons and the capitula for the hours of prime and none (see Divine Office) to examples of known uses, but more reliable systems for identifying lesser-known uses continue to be explored.