Canon 350. §1 The College of Cardinals is divided into three orders: the episcopal order, to which belong those Cardinals to whom the Roman Pontiff assigns the title of a suburbicarian Church, and eastern-rite Patriarchs who are made members of the
College of Cardinals; the presbyteral order, and the diaconal order.

§2 Cardinal priests and Cardinal deacons are each assigned a title or a deaconry in
Rome by the Roman Pontiff.
[NB see Rescript “ex audientia Ss.mi” of 26 June 2018 by which four Cardinals were coopted into the Order of Bishops and made equivalent to Cardinals who hold the title of a suburbicarian Church, in derogation of can. 350 §§1-2 and 352 §§2-3
(Communicationes 50 (2018), pp. 431-432).]

§3 Eastern Patriarchs within the College of Cardinals have their patriarchal see as a title.

§4 The Cardinal Dean has the title of the diocese of Ostia, together with that of any other Church to which he already has a title.

§5 By a choice made in Consistory and approved by the Supreme Pontiff, Cardinal priests may transfer to another title; Cardinal deacons may transfer to another deaconry and, if they have been a full ten years in the diaconal order, to the presbyteral order: priority of order and of promotion is to be observed.

§6 A Cardinal who by choice transfers from the diaconal to the presbyteral order, takes precedence over all Cardinal priests who were promoted to the Cardinalate after him.

§1. Cardinalium Collegium in tres ordines distribuitur: episcopalem, ad quem pertinent Cardinales quibus a Romano Pontifice titulus assignatur Ecclesiae suburbicariae, necnon Patriarchae orientales qui in Cardinalium Collegium relati sunt; presbyteralem et diaconalem.

§2. Cardinalibus ordinis presbyteralis ac diaconalis suus cuique titulus aut diaconia in Urbe assignatur a Romano Pontifice.

§3. Patriarchae orientales in Cardinalium Collegium assumpti in titulum habent suam patriarchalem sedem.

§4. Cardinalis Decanus in titulum habet dioecesim Ostiensem, una cum alia Ecclesia quam in titulum iam habebat.

§5. Per optionem in Consistorio factam et a Summo Pontifice approbatam, possunt, servata prioritate ordinis et promotionis, Cardinales ex ordine presbyterali transire ad alium titulum et Cardinales ex ordine diaconali ad aliam diaconiam et, si per integrum decennium in ordine diaconali permanserint, etiam ad ordinem presbyteralem.

§6. Cardinalis ex ordine diaconali transiens per optionem ad ordinem presbyteralem, locum obtinet ante omnes illos Cardinales presbyteros, qui post ipsum ad Cardinalatum assumpti sunt.