A designated spot is where you are selected to be positioned, preferably by God to stay in that area till ones term is over. This could be a spot in class, where you sit at lunch, where you stand in line-up when warming up.
E.g. Matt was not designated to that spot in line so he was asked to move.
E.g. This is a designated area sorry.
E.g. Designated dog.
E.g. When you are in your designated area things just go smoother.