VATICAN CITY, Feb. 16 (RNS) -- Next to the office of pope, the College of Cardinals is the most powerful institution in the Roman Catholic Church, made up of top administrative officials and bishops who govern major sees throughout the world.

The cardinals, members of an exclusive international men's club, serve both as the electors and the advisers of popes.

Known even today as "princes of the church," cardinals were the courtiers of the papal court during the Middle Ages. They ranked alongside kings and above secular princes.

Under Canon (church) Law, the first duty of the College of Cardinals is to elect the pope from among its own members. This means that by entering the college, a cardinal automatically becomes eligible for the church's highest office.

Once dominated by Italian prelates, the College of Cardinals has become increasingly international through a series of reforms carried out by John XXIII and Paul VI.

The reforms set the stage for the surprise election in 1978 of Karol Wojtyla, archbishop of Cracow, the first non-Italian pope in four and a half centuries and the first Polish pope in history. As Pope John Paul II, Wojtyla has pushed the reforms even further.

The name cardinal comes from cardo, the Latin word for hinge. A Vatican commentary on the Code of Canon Law points out that a hinge has two functions. "It serves as a pivot on which, for example, a door swings in a doorjamb; it also attaches the door (something from outside the door jamb itself) to the wall."

The word dates to the early church when a cleric normally served for life in the post to which he was ordained and was known as the titular because he held title to the post. If he moved to another post, he was "incardinated" like a hinge attaching a door to a wall.

The clerics who were transferred usually had outstanding ability, which bishops wanted to take advantage of. They became aides and advisers, and their views were the pivots on which the outcome of an issue might swing.

The cardinals' role as advisers to the pope, either in formal gatherings called Consistories or in individual audiences, was considered so crucial that at one time a cardinal needed papal permission to leave Rome even if he was attached to another see and was simply visiting the Eternal City.

By the time of Gregory the Great, who reigned as pope from 590 to 604, the title of cardinal was accepted throughout the church.The College of Cardinals is divided into ranks called episcopal, presbyteral and diaconal.

The cardinal bishops of the episcopal rank are oriental patriarchs, who retain title to their patriarchal sees, and cardinals whom the pope makes titular bishop of one of the seven ancient "suburbicarian" dioceses nearest to Rome.

The cardinals with title to suburbicarian dioceses choose from among themselves a dean and assistant dean of the college to preside as the first among equals over the Conclaves that elect popes and other meetings of the cardinals.

The pope names cardinal priests of the presbyteral rank to titular churches in Rome where their main duty is to offer financial support while the cardinal deacons, who are members of the church's central administrative offices known as the Roman Curia, receive assignments to aid stations that were staffed by deacons in early medieval Rome.

The senior cardinal deacon also has the privilege of announcing the election of a pope. By tradition, he appears on the balcony above the main entrance to St. Peter's Basilica and tells the crowd in the square below, "I announce to you a great joy. We have a pope."

It is up to the pope to decide how many members to name to the College of Cardinals. In the 16th century Pope Sixtus V set a limit of 70, which John XXIII removed. Paul VI then set a ceiling of 120 electors, but with next week's Consistory, the electors will number 135.

The Consistory will be the eighth that John Paul has called to name new cardinals in the 22 years of his papacy. By comparison, Pius XI called 17 consistories in 17 years, Pius XII only two in 20 years.