Game concept
Known
From the game's encyclopedia
A Known Tenet Status means the Rite is aware of this Tenet or Doctrine, but neither endorses nor permits its practice. It can be considered when authoring or diverging the Rite, and may be raised to a higher Tenet Status.
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.
Known is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "A Known Tenet Status means the Rite is aware of this Tenet or Doctrine, but neither endorses nor permits its practice." 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.