Air Traffic Control (ATC) consists of one or more Controllers, located in the ATC Tower, who will be in charge of clearance delivery, ground movement control, and runway control.  In some cases ATC also assumes responsibility for Apron Control, while in other cases, this responsibility is managed by the Airport Operator. Both ATC and the Airport Operator ensure the efficient movement of aircraft within their area of responsibility, in order to provide a continuous flow of aircraft in accordance with expected traffic demand. - [EUROCONTROL Specification for A-CDM v0.8]