Official rule text
24.2 To resolve the primary ability on the “Construction” strategy card, the active player may place either one PDS or one space dock on a planet they control. Then, that player may place an additional PDS on a planet they control. a The structures can be placed on the same planet or different planets. b The structures can be placed in any systems, regardless of whether the player has a command token in the system or not.
View official source
Source: Living Rules Reference and FAQ - Prophecy of Kings
Expansion: Prophecy of Kings
Version: 2.0
Reference: Rule 24.2