[1][2] Before the motu proprio Pontificalis Domus of 28 March 1968, Honorary Prelates (HP) were called Domestic Prelates (Latin: Antistites Urbani).
Those who held certain offices were also granted the title, such as an Archbishop or Bishop Assistant at the Pontifical Throne or a member of the Roman Prelature.
The title was retained by archbishops, bishops and protonotaries apostolic who had been awarded it before their appointment to those positions.
[3] The Prelates of Honor are entitled Reverend Monsignor.
Historically associated with the chamberlain of the papal court, it is the second rank of monsignor: above Chaplain to His Holiness, but below Protonotary Apostolic.