A plate that covers a BacklightAn aperture provided at the rear of certain lamps, usually on Semaphore Signals or Ground Position Light Signals to enable the Signaller to see that the Signal ... More to enable the SignallerA person responsible for the operation of the Signalling System, to safely control the passage and regulation of trains, usually located in a Signal Box. More to see that a
Semaphore SignalA Signal which informs a driver by means of the position of a mechanical arm during daylight and coloured lights during darkness. More has correctly cleared to the Off position.