The increasing involvement of the cardinal bishops in the administration of the papal curia resulted in a detachment from their dioceses. Therefore, some of them, in particular the cardinal-bishops of Sabina and Velletri, have for centuries had
auxiliary bishops and in 1910
Pope Pius X's
apostolic constitution Apostolicae Romanorum made this practice obligatory for all suburbicarian dioceses. In 1962,
Pope John XXIII in his decree
Suburbicarii sedis made the cardinal bishops into titular bishops and made provision for the appointment of separate residential diocesan bishops for Velletri-Segni, Porto-Santa-Rufina, Frascati, Palestrina, Albano and Sabina. For the
diocese of Ostia – the titular diocese of the
dean of the College of Cardinals – no resident diocesan bishop was appointed; it is entrusted to an
apostolic administrator, which is always the
cardinal vicar of Rome. Though the diocesan bishops exercise all episcopal administrative functions, the cardinal bishops still formally take possession of their titular dioceses. == See also ==