Free upkeep in cities/castles

[EnDSchultz]

Hey, I did a quick search and turned up nothing on this, though I'm pretty terrible with the search feature so it's undoubtedly been asked before at some point. Just a simple question: when a unit card states in the description it gets free upkeep (knights in castles, urban militia in towns), does that mean that all units of those types in their respective settlements will receive free upkeep no matter how many, or does it still only apply to the blue "free upkeep" slots?

[preachercheeze]

only the blue slots are free upkeep...