VATICAN CITY (CNS) – While the surprise resignation of Pope Benedict XVI is a first for the Church in centuries, it also leads to a complicated period of transition that ends in the election of a new pope.

Regulated by ancient traditions and recent rules, the period between popes – known by the Latin term “interregnum” – will begin exactly at 8 p.m. Rome time Feb. 28, a date and time Pope Benedict stipulated for when the See of Rome and the See of St. Peter will be vacant.

Normally the interregnum begins with a pope’s death and is followed by a period of mourning.

This time, the pope will resign from his ministry and spend a short period of prayer and reflection at the papal summer villa in Castel Gandolfo, south of Rome, before moving to a monastery at the Vatican.

The rules governing the interregnum are matters of Church law, not dogma.

The apostolic constitution “Universi Dominici Gregis” confirms that as long as the Holy See is vacant, the universal Church is governed by the College of Cardinals, which cannot, however, make decisions normally reserved to the pope. Such matters must be postponed until the new pope is elected.

Until there is a pope, the Roman Curia – the Vatican’s network of administrative offices – loses most of its cardinal supervisors and cannot handle any new business.

The College of Cardinals is to deal solely with “ordinary business and matters which cannot be postponed.” At present, there are 209 cardinals, and all of them are asked to meet in Rome to help administer the transition period.

The College of Cardinals does this through two structures: a general congregation, in which all the cardinals are to meet daily; and a particular four-member congregation, consisting of the chamberlain of the Holy Roman Church, Cardinal Tarcisio Bertone, and a rotating team of three cardinal assistants.