When Pope Pius V made the Roman Missal mandatory for all Catholics of the Latin Church, he permitted the continuance of other forms of celebrating Mass that had an antiquity of at least two centuries. The rite used by the Carthusians was one of these, and still continues in use in a version revised in 1981. Apart from the new elements in this revision, it is substantially the rite of Grenoble in the 12th century, with some admixture from other sources. According to current Catholic legislation, priests can celebrate the traditional rites of their order without further authorization.