Since the position of Pope is required to be "usque ad mortem" (until death), when the Pope of Rome resigns, quits, or is removed from his Pontificate before his natural death, such leaving of office is known as Pontificatus Interruptus.
Due to his resignation from office, Pope Benedict XVI, whose previous name was title and name was Cardinal Ratzinger, will forever be known as Pontificatus Interruptus.
by Neologian-PJG February 11, 2013