A function that, under ordinary operation, is operated automatically by the
passage of trains and is not interlocked with any other Signalling FunctionA Signal, set of Points or other part of the train control system. More.
The function is generally associated with a particular Signal BoxThe building in which the Signaller(s) is/are situated together with the control and indication system for the signalling. See also Signalling Centre. More from which
its operation is supervised, unless some form of local monitoring is
provided.