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A small white light below a main aspect.
Also known as: Calling-on signal, Shunt ahead signal
A British signal mounted below a main aspect authorising a movement past it under a restriction, without clearing the main signal.
Authorises a movement past a signal that remains at danger, under a restriction stated by the rule book.
Contexts: Public information
Exists so that a train may be admitted to an occupied platform or section without the main signal ever showing a proceed aspect, keeping the main aspect's meaning absolute.
Contexts: Public information
A small head of lights mounted beneath the main signal head, showing only when the main signal remains at its most restrictive aspect.