Game concept
Papal Bull
The game also links it as Papal Bulls, Bull, Bulls.
From the game's encyclopedia
A Papal Bull is a solemn decree of the Head of Faith of a Christian Faith, backed by the authority of The Christian Church.
A Christian Head of Faith with sufficient Church Authority may proclaim a Bull through the Enact a Bull Decision, spending Piety to:
• Summon a Great Holy War
• Declare a Tenet Permitted or Prohibited
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Papal Bull is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Papal Bull is a solemn decree of the Head of Faith of a Christian Faith, backed by the authority of The Christian Church." It is part of The Christian Church. The game also links it as Papal Bulls, Bull and Bulls. Patch 1.20.1.2, from game/common/game_concepts/pam_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/pam_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.