A number of vehicles have been made with an independent drum brake on the transmission output shaft. It is called a driveline parking brake. This is completely independent of other braking systems. This brake is effective till drive train is intact. This type of parking brake is used by either a foot pedal or a hydraulic cylinder.
The integral brake is a kind of parking brake on the inside of the disk brake system. This system usually has cables to engage the parking brake as the normal drum brake system. There are usually two brake shoes in the rear drum. When the parking brake is pulled, it lets a cable tighten up the shoes so they press against the drum, holding or stopping the vehicle.