19. It belongs only to an ecumenical council or to the Apostolic See to determine, transfer or suppress feast days common to all the Eastern Churches. On the other hand, to determine, transfer or suppress the feast days of any of the individual churches is within the competence not only of the Apostolic See but also of the patriarchal or archiepiscopal synod, due regard being had to the whole area and the other individual churches.24

20. Until such time as all Christians are agreed on a fixed day for the celebration of Easter, with a view meantime to promoting unity among the Christians of the same area or nation, it is left to the patriarchs or supreme authorities of a place to come to an agreement by the unanimous consent and combined counsel of those affected to celebrate the feast of Easter on the same Sunday.25

21. Individual faithful dwelling outside the area or territory of their own rite may follow completely the established custom of the place where they live as regards the law of the sacred seasons. In families of mixed rite it is permissible to observe this law according to one and the same rite.26

22. Eastern clerics and Religious should celebrate in accordance with the prescriptions and traditions of their own established custom the Divine Office, which from ancient times has been held in high honor in all Eastern Churches.27 The faithful too should follow the example of their forebears and assist devoutly as occasion allows at the Divine Office.

23. It belongs to the patriarch with his synod, or to the supreme authority of each church with the council of the hierarchs, to regulate the use of languages in the sacred liturgical functions and, after reference to the Apostolic See, of approving translations of texts into the vernacular.28