Before revision: Navigation systems may be entirely on board a vehicle or vessel ( on the ships) bridge , or they may be located elsewhere and communicate via radio or other signals with a vehicle or vessel, or they may use a combination of these methods.
After revision: Navigation systems may be entirely on board a vehicle or vessel ( for example, on the ship's bridge) , or they may be located elsewhere and communicate via radio or other signals with a vehicle or vessel, or they may use a combination of these methods.