Particular Churches, in which and from which the one and only Catholic Church exists, are principally dioceses. Unless the contrary is clear, the following are equivalent to a diocese: a territorial prelature, a territorial abbacy, a vicariate apostolic, a prefecture apostolic and a permanently established apostolic administration. (Code of Canon Law, canon 368)
Second Vatican Council, Dogmatic Decree on the Church Lumen gentium, 23
"The particular Churches, insofar as they are 'part of the one Church of Christ' (Second Vatican Council: Decree Christus Dominus, 6/c), have a special relationship of mutual interiority with the whole, that is, with the universal Church, because in every particular Church 'the one, holy, catholic and apostolic Church of Christ is truly present and active' (Second Vatican Council: Decree Christus Dominus, 11/a). For this reason, the universal Church cannot be conceived as the sum of the particular Churches, or as a federation of particular Churches. It is not the result of the communion of the Churches, but, in its essential mystery, it is a reality ontologically and temporally prior to every individual particular Church" (Communionis notio, 9).
Second Vatican Council, Decree on the Pastoral Office of Bishops in the Church Christus Dominus,11
