[1] In a larger archdiocese, they might be assigned to serve a portion of the archdiocese (sometimes called deaneries, regions, or vicariates) or to serve a particular population such as immigrants or those of a particular heritage or language.
Canon law recommends that the diocesan bishop appoint an auxiliary bishop as vicar general of the diocese.
[2] In May 2017, Gregorio Rosa Chávez was one of the first Roman Catholic auxiliary bishops to be appointed as cardinal.
At that time, he was auxiliary bishop of José Luis Escobar Alas, the Archbishop of San Salvador[3] (who was not elevated).
The Greek word protosyncellus defines an auxiliary bishop who has been elevated to the dignity of vicarian of another titular bishop, and who is assigned to assist and act on behalf of his episcopal authority over the jurisdiction of the episcopal see.