may be ordained to each of the three orders only once. They also consider that ordination can be conferred only on males. Priests in service outside their diocese Although priests are incardinated into a diocese or order, they may obtain the permission of their diocesan ordinary or religious superior to serve outside the normal jurisdiction of the diocese or order. These assignments may be temporary or more permanent in nature. Temporary assignments may include studying for an advanced degree at a Pontifical University in Rome. They may also include short-term assignments to the faculty of a seminary located outside the diocese's territory. Long-term assignments include serving the universal church on the staff of a dicastery or tribunal of the Roman Curia or in the diplomatic corps of the Holy See. They may also be appointed the rector or to long-term teaching assignments to the faculty of a seminary or Catholic university. Priests may also serve on the staff of their episcopal conference, as military chaplains in the military ordinariates, or as missionaries. Positions within a diocese at diocesan level The diocesan bishop appoints a vicar general to assist him in the governance of the diocese. Usually, only one vicar general is appointed; particularly large dioceses may have more than one vicar general. The vicar general or one of them is usually appointed moderator of the curia who coordinates the diocesan administrative offices and ministries. A diocesan bishop can also appoint one or more episcopal vicars for the diocese. They have the same ordinary power as a vicar general, however, it is limited to a specified division of the diocese, to a specific type of activity, to the faithful of a particular rite, or to certain groups of people. Vicars general and episcopal vicars must be priests or bishops. In the Eastern Catholic Churches, they are called protosyncelli and syncelli (canon 191 of the Code of Canons of the Eastern Churches). Diocesan bishops are required to appoint a judicial vicar to whom is delegated the bishop's ordinary power to judge cases (canon 1420 of the 1983 Code of Canon Law, canon 191 of the Code of Canons of the Eastern Churches). In the Latin church, the judicial vicar may also be called officialis. The person holding this post must be a priest, have earned a doctorate in canon law (or at least a license), be at least thirty years old, and,