Game concept
Unknown
From the game's encyclopedia
An Unknown Tenet Status means the Rite has no awareness of this Tenet or Doctrine at all. Adherents of the Rite do not implicitly know it, and cannot pick it when creating a new Rite or as a Personal Tenet.
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.
Unknown is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "An Unknown Tenet Status means the Rite has no awareness of this Tenet or Doctrine at all." It is part of Tenet Status. 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.