"Empire Unique" and "Planet Unique" flags. Verification.

[WarStalkeR]

Luckily I found out that if a certain upgrade chain of structures has Empire Unique flag (i.e. Control Center I, II, III & etc), game engine automatically prevents you from building more basic structures from same chain if you already have more advanced ones.

For example, if I already have Control Center IV, I can't build Control Center I or upgrade Management Center into Control Center I.

And I'll be happy if somebody from the Stellaris Developers can verify that it is indeed intended by design and not just "nice" some random feature that eventually will be removed from the game.

 

[Iyur]

It's described in buildings section, for example:

building_institute = {
    base_buildtime = 720
    empire_unique = yes
}