Basically entities that can only be triggered by a specific team / that only affect a specific team. On the mapper's side, it'd be as simple as giving a button (or door or trigger_hurt or...) a 'team' property. Preferably this'd be expandable to accept 'team', 'team2', 'team3' to be able to deny access to a team as well. How team keys would affect some entities has yet to be discussed.