Artillery communication letter codes

You sometimes come across the letter codes used by the artillery when communicating between units or with the aircraft of the Royal Flying Corps or Royal Air Force that flew observations missions to co-ordinate artillery fire. These codes are not always easy to interpret. This list comes from the private papers of 45222 Wireless Operator A. R. Atkinson RAF, held at the Imperial War Museum as document 89/12/1.

AR      Air
AA      Anti aircraft guns
RUF    Are you firing?
B         Are you receiving my signals?
CI        Am returning to landing ground
KQ      Are you ready to fire?
ART    Artillery
BF       Battery fire
CAV   Cavalry
X         Change to
COL    Column
GO      Go on firing in your own time
G         Fire
GF       Fire for effect (fleeting opportunity signal)
LL       All available batteries to open fire (sudden or very favourable target)
XX      Practice LL call
T          General answer (or RD)
N         Guns in position at
NF       Guns now firing in position at
MM     Trench mortars now firing in position at
NT       Guns not firing at
GZ       Graze
L          High Explosive
FAN    Infantry
MT      Mechanical transport
Ht        Horse Transport
M         Mostly (as in mostly graze) or Mean point of impact
QM      More left
KKH   Sound ranging section standby
P          Percussion
W        Short unobserved or washout
VO      Salvo
A         Standby
MQ      Stop firing or wait
SW      Switch
EA       Enemy aircraft
TNK    Tanks
Ok       Range (target)
Z          Smoke shell
O         Over
S          Short
R         Right
KB      Continue firing with balloon observation
Q         Left
RR       More right
QQ      More left
J           Just
F          ?
SC       Smoke cloud obscuring target
ASF     Sent when battery is firing for effect and observer wishes to range the guns afresh
SOS     Barrage fire
WPNF Many batteries in square active (followed by location of square)

Weather codes

NBG   No good for anything
DUD   ditto
NGR   No good for registration
NGP    No good for photography
OK      Fit
VIS     Visibility
UL       Unfit for counterbattery work
FL       Fit for ditto
UE       Unfit for registration
FR       Fit for ditto
UD      Unfit for photography
FD       Fit for ditto
C         Clouds
40        4000 (feet height of clouds)
Up       Unfit for patrol

FP        Fit for ditto