Signalling Equipment Meaning of alphabets used to denote Signalling Information

A – Approach, Automatic. Near endpoint.
B – Block positive energy, Far-end point.
C – CONTACT. Center, Check.

D – CLEAR, GREEN
E – EARTH, LAMP
F – FRONT, FUSE
G – SIGNAL, GATE

H – CAUTION YELLOW.
HH – ATTENTION, DOUBLE YELLOW
I – CURRENT,

J – TIME DELAYED ACTION
K – INDICATION
L – LOCKING
M – MOTOR, MARKER

N – NORMAL, NEGATIVE
P – PUSH, REPEATER, POWER.
Q – SECONDARY, COIL.

R – RELAY, RED, RIGHT, REVERSE.
S – STICK
T – TRACK, TIME, TERMINAL

U – ROUTE, UNIT.
W – POINT, SWITCH
X – BELL, BUZZER, CROSSING, INTERLOCKING
Y – SLOT, RELEASE
Z – USES FOR ANY SPL TERM.

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Code for Designation of Colours In Railway Signalling

COLOUR –  LETTER CODE
Black – BK
Blue (Including Light Blue) – BU
Brown – BN
Gold – GD
Green – GN

Grey (Slate) – GY
Orange – OG
Pink – PK
Red – RD
Silver – SR

Turquoise – TQ
Violet (Purple) – VT
White – WH
Yellow – YE
Green and Yellow – GNYE