Game concept · All Under Heaven

Imperial Policy

The game also links it as Imperial Policies.

From the game's encyclopedia

The Imperial Policy is a Law set by the Top Liege of Japan that applies to all Vassals. Different policies may restrict or allow actions, or bestow Realm-wide effects.

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.

Imperial Policy is an entry of Crusader Kings III's in-game encyclopedia (All Under Heaven). The game explains it: "The Imperial Policy is a Law set by the Top Liege of Japan that applies to all Vassals." The game also links it as Imperial Policies. Patch 1.20.1.2, from game/common/game_concepts/tgp_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.

for a guide, post or blog

Source: game/common/game_concepts/tgp_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.