VATICAN CITY (CNS) — In their general congregation meetings, in liturgical processions and in the Sistine Chapel, every cardinal has a place and each cardinal knows his place. The Vatican calls it "precedence," and it has little to do with the importance of the cardinal’s day job, the size of his diocese or his age. But it has everything to do with timing. Cardinals are divided into a three-tier internal hierarchy: cardinal bishops, cardinal priests and cardinal deacons. It’s the seating order for the general congregations in the Vatican synod hall. It will be the order they line up in for the procession at the Mass for the election of a new pope.The four patriarchs of Eastern Catholic churches who are cardinals are inserted in the ranking between the cardinal bishops and cardinal priests.

Simply skipping the cardinals who were over 80 years of age as of Feb. 28, the precedence is the order the cardinal electors will process into the Sistine Chapel for the conclave, the order that determines where they will sit inside and the order in which they will cast their ballots.

The cardinal bishops are six senior Latin-rite cardinals residing in Rome; one of them, Cardinal Angelo Sodano, is dean of the College of Cardinals. Diocesan bishops make up the bulk of the rank of cardinal priests, while cardinal deacons are mostly officials of the Roman Curia.

Within each of the three ranks — cardinal bishops, priests and deacons — precedence is determined by who has been a cardinal the longest. That may be literally a matter of seconds.

Canadian Cardinal Thomas C. Collins of Toronto is ranked above Cardinal Timothy M. Dolan of New York; when Pope Benedict XVI announced the names of the cardinals he was creating at a Feb. 18, 2012, consistory, he read Cardinal Collins’ name a few seconds before Cardinal Dolan’s.

Episcopal longevity, not alphabetical order, was the deciding factor.

Cardinal Collins had been ordained a bishop in 1997, while Cardinal Dolan became a bishop in 2001.

Only two of the cardinal bishops are under 80 and eligible to enter the conclave to vote for the next pope: Italian Cardinals Giovanni Battista Re, former prefect of the Congregation for Bishops; and Tarcisio Bertone, the camerlengo or chamberlain of the church.

Cardinal Sodano, the dean, is leading the general congregation meetings that precede the conclave. All cardinals, including those over 80, may participate. Because Cardinal Sodano is 85, he will stay outside the Sistine Chapel with the other elders, and the duties of the dean will pass to the second in rank, Cardinal Re.

The precedence also determines one of the best supporting-cardinal roles. The "proto-deacon" or top-ranking cardinal deacon is the one who has the honor of walking out onto the balcony of St. Peter’s Basilica and announcing to the world, "Habemus papam," "We have a pope."

Currently, the post is held by French Cardinal Jean-Louis Tauran, president of the Pontifical Council for Interreligious Dialogue, who has been a cardinal since 2003.

The first five cardinal electors in order of precedence are: Cardinals Re; Bertone; Antonios Naguib, retired Coptic Catholic patriarch; Bechara Rai, the Maronite patriarch; and Godfried Daneels, former archbishop of Mechelen-Brussels.

The last cardinal elector in rank is U.S. Cardinal James M. Harvey, archpriest of the Basilica of St. Paul Outside the Walls. He will walk into the Sistine Chapel behind: Brazilian Cardinal Joao Braz de Aviz, prefect of the Congregation for Institutes of Consecrated Life and Societies of Apostolic Life; U.S. Cardinal Edwin F. O’Brien, grand master of the Equestrian Order of the Holy Sepulchre of Jerusalem; Italian Cardinal Domenico Calcagno, president of the Administration of the Patrimony of the Holy See; and Italian Cardinal Giuseppe Versaldi, president of the Prefecture for the Economic Affairs of the Holy See.