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 it self in “operational” and “non-opera tional” (informative) depending on whether the train traffic automation systems permit or not a direct control action on the signaling. See Regulation.
