The following abbreviations apply –
A Albacore NN1
AB Pole AB Class B
AS Asymmetric Class A
C Cadet Class Y
CL1 Cruiser Class 1 Pdt 1
CL2 Cruiser Class 2 Pdt 2
CL3 Cruiser Class 3 Pdt 3
CL4 Cruiser Class 4 Pdt4
D Dolphin Class G
DT Dart Class D
E Enterprise Class E
FB Fireball Class Pdt 8
FF Flying Fifteen Class NN6
J24 J24 Class J
L Laser Class W
R Merlin Rocket Class O
R2 RS 200 Class (DC) R
RS RS 400 Class NN2
S Shrimper Class Q
T Topper Class T
W Wayfarer Class V
X X One Design Class NN5
4.7 Laser 4.7 Class Pdt7
420 420 Class (YDC) K

Class flags will be used as Warning signals unless the Sailing Instructions advise otherwise e.g. For combined class starts.