the 16th century and after, such as the Jesuits and Redemptorists, followed this same general format, though some added a "fourth vow", indicating some special apostolate or attitude within the order. Fully professed Jesuits (known as "the professed of the fourth vow" within the order), take a vow of particular obedience to the Pope to undertake any mission laid out in their Formula of the Institute. Poor Clares additionally profess a vow of enclosure. The Missionaries of Charity, founded by St. Teresa of Calcutta centuries later (1940s) take a fourth vow of special service to "the poorest of the poor". In the Catholic Church In the Catholic Church, the vows of members of religious orders and congregations are regulated by canons 654-658 of the Code of Canon Law. These are public vows, meaning vows accepted by a superior in the name of the Church, and they are usually of two durations: temporary, and, after a few years, final vows (permanent or "perpetual"). Depending on the order, temporary vows may be renewed a number of times before permission to take final vows is given. There are exceptions: the Jesuits' first vows are perpetual, for instance, and the Sisters of Charity take only temporary but renewable vows. Religious vows are of two varieties: simple vows and solemn vows. The highest level of commitment is exemplified by those who have taken their solemn, perpetual vows. There once were significant technical differences between them in canon law; but these differences were suppressed by the current Code of Canon Law in 1983, although the nominal distinction is maintained. Only a limited number of religious congregations may invite their members to solemn vows; most religious congregations are only authorized to take simple vows. Even in congregations with solemn vows, some members with perpetual vows may have taken them simply rather than solemnly. A perpetual vow can be superseded by the Pope, when he decides that a man under perpetual vows should become a Bishop of the Church. In these cases, the ties to the order the new Bishop had are dissolved as if the Bishop had never been a member; hence, such a person as Pope Francis, for example, has had no formal ties to his old order for years. However, if the Bishop was a member in good standing, he will be regarded, informally, as "one of us", and he will always be welcome in