Typical expression in cybernetics and systems theory, which designates the detection of the output (response) signals of a system to perform evaluation, decision and modification activities on input signals (input). More generally, it refers to a “control system”. In relation to train running, the Control can better specify itself in “operational” and “non-operational” (informative) depending on whether the train traffic automation systems (V.) permit or not a direct control action on the signaling. V. Regulation
