Official rule text
16.2 The combined capacity values of a player’s ships in a system 17.5 While a unit is captured, it cannot be produced or placed by its determine the number of fighters and ground forces that player original owner until it is returned. can have in that system’s space area.
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Source: Twilight Imperium: Fourth Edition - Living Rules Reference: Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 16.2