1. A method of monitoring a functioning of a system, the system one of including a lower-level subsystem and being a component of a higher-level system, the system further including hardware components, including at least one of sensors, actuators and function computers, the method comprising: checking input signals, output signals, and functions of the system; providing a plurality of decentralized monitoring functions in individual ones of the functions of the system for monitoring a functioning of the individual ones of the functions of the system; and providing at least one higher-level, functions-overreaching monitoring instance for coordinating the plurality of decentralized monitoring functions.