Game concept

Domicile Building Slot

The game also links it as Domicile Building Slots, Slot, Slots.

From the game's encyclopedia

Each Domicile has only a limited number of potential Slots for new buildings.

New Slots can be unlocked by upgrading the central Domicile Building, like an Estate's Villa or a Camp's Pavilion.

Locked Slots are shown in the Domicile view — there is no way to get extra Slots beyond these.

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.

Domicile Building Slot is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Each Domicile has only a limited number of potential Slots for new buildings." It is part of domicile_buildings. The game also links it as Domicile Building Slots, Slot and Slots. Patch 1.20.1.2, from game/common/game_concepts/07_ep3_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.

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Source: game/common/game_concepts/07_ep3_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.