Signalling Nomenclature

Individual signalling elements (signals, track circuits, points, level crossings) are identified by means of standard nomenclature. The trackside equipment, which generates the data for the signalling elements, may include solid-state interlocking (SSI) outputs, relay contacts, push buttons, levers and other indications. In SOP's and ECS's, the first letter denotes the general kind of the element. Preceding letters denote the function of the element. This is not always the case, as some labels don't have the first letter.

Meaning of the first letter:

Code	Meaning
L	Level Crossing
P	Points
R	Route
S	Signal
T	Track Circuit

Signals

Code	Meaning
BR, R	Repeater signal
RGE	Electric lamp illuminating danger aspect (Red)
HGE	Electric lamp illuminating caution aspect (Yellow)
DGE	Electric lamp illuminating clear aspect (Green)
RGK	Electro-mechanical indicator, signal showing danger aspect (Red)
HGK	Electro-mechanical indicator, signal showing caution aspect (Yellow)
DGK, OFFK	Electro-mechanical indicator, signal showing clear aspect (Green)
OFFG	Signal apparatus OFF, signal showing clear aspect (Green)
LOSECK	Electro-mechanical indicator, Limit of Shunt

Points

Code	Meaning
GF	Ground Frame
FK	Electro-mechanical indicator, Ground Frame points locally operated
N	Normal position
NK	Electro-mechanical indicator, normal position
NWK	Electro-mechanical indicator, points operating apparatus in normal position
R	Reverse position
RK	Electro-mechanical indicator, reverse position
RWK	Electro-mechanical indicator, points operating apparatus in reverse position