A Annunciators, electric light block signals, switch indicator, tower indicators
B Relays Interlocking, line, neutral, polarized, slow release, time, track
C Circuit controlling and circuit breaking devices Switch box and commutator, lever lock, electric table levers for power operated signals, track instruments and trolley contacts
D Cable poles, indicators, relay boxes, foundation bases, pinnacles, cable outlets, ventilators
E Highway crossing alarms Mechanically operated crossing bells, tower bells, crossing signs, illuminated signs
F Electric bells Annunciator bells, indicator bells, electric flag, time bell, highway crossing bells, locomotive type bells, motor type bells
G Track circuit and construction material cross arms, pole steps, trunking, bond wires, channel pins, lineman's tools
H Insulated rail joints, switch wedge blocks, hand car and velocipede axle insulator
I Lightning arresters, terminals, connectors, ground tubes and rods, tags, wires, locks, steel stencils, solder
J Batteries and accessories
K Relay boxes and accessories
L Battery receptacles
M Ground signals Lower/upper quadrant, wire/pipe operated
N Bridge and bracket signals Lower/upper quadrant, wire/pipe operated
O Dwarf and pot signals
P Station signals Train order, flag station
Q Signal and switch operating levers Table, wall, floor, ground
R Mechanical signal accessories Masts, bases, pinnacles, slots, ladders, operating rods, spectacles, semaphore blades, dummy masts, bracket posts
S Mechanical ground and leadout connections Crank stands and compensators, bridge couplers and locks, turnbuckles, eye rods, jaws, pipe, stuffing boxes, signal wire
T Switch operating and locking devices Switch layouts, rail clips, detector bars, switch and lock movements, locks, front rods, lock rods, tie rods, throw rods
U Bridge warnings
X Miscellaneous Freight house trucks, jacks, wrenches, vises, anvils, copying presses