The Signalling Record Society

Archive Categories

Within the catalogue listings documents are coded so as to give an indication of what they will contain. These codes are set out here.

Code	Explanation
ARCH	Architectural drawing.
CIRC	Circuit diagram.
DET	Detection table - electrical and/or mechanical.
ELEC	Electrical control table.
LAYOUT	Layout diagram - plan showing track layout (not to scale) without signalling detail.
LEVER	Lever locking table - equivalent for an all-electric frame.
MAP	Map.
MECH	Mechanical locking - tables and/or chart.
MISC	Anything not covered in the other categories. Further explanation often included.
NUMB	Numbering plan - diagram showing numbers of functions, not to scale.
ROUTE	Route locking table.
SBD	Signalbox diagram - as displayed in the box, or an office copy of that.
SCALE	Scale plan of railway property.
SCHEME	Scheme diagram - plan showing (actual or proposed) alterations, typically with new work in red.
SK	Sketch diagram - properly drafted diagram, to scale longitudinally, showing track layout and full signalling details.