C'Ship
M = The Mintex British Historic Rally Championship    
NH = The Motoscope Northern Historic Rally Championship    

Class
B2 = Cars up to 1000cc & 1001cc to 1300cc    
B3 = 1301cc to 1600cc (excluding twin cam engined cars)    
B4 = 1601cc to 2000cc (Including twin cam engined cars but excl Porsche 911's)    
B5 = Cars over 2000cc including all Porsche 911's    
C2 = Up to 1300cc & 1301cc to 1600cc (excluding twin cam engined cars)    
C3 = 1601cc to 2000cc    
C5 = Over 2000cc, all and multi valve Twin Cam engined cars    
D2 = Up to 1300cc & 1301cc to 1600cc including 2 valve twin cam engined cars)    
D3 = 1601cc to 2000cc    
D4 = over 2000cc including twin cam multi valve engined cars    
D5 = All other twin cam multi valve engined cars    
E1 = Cars up to 1600cc    
E2 = Cars over 1601cc    
F1 = Cars up to 1600cc    
F2 = Cars over 1601cc    
G1 = Cars up to 1600cc    
G2 = Cars over 1600cc    
Z1 = For 2wd cars registered before 31 December 1990, not conforming to MSA R49. Cars up to 1600cc.    
Z2 = For 2wd cars registered before 31 December 1990, not conforming to MSA R49. Cars over 1600cc    
LR1 = British Armed Forces Motoring Association    
LR2 = Invited Land Rovers of similar type to BAFMA specification    

C'Ship
G = RAVENOL BTRDA Gold Star Championship    
S = RAVENOL BTRDA Silver Star Championship    
P = BTRDA Production Cup    
K = Thomas Panels BTRDA 1400 Championship    
F = BTRDA Rally First Championship    
H = BTRDA Historic Cup    
D = DMack ST Trophy    
E = The 2017 Maxxis Tyres MSA English Championship    
A = The ANCC Chonka Stage Rally Championship 2017    
AC = The ANWWC Forest Rally Championship 2017    
AN = The ANECCC SG Petch Stage Rally Championship    
Z = MG ZR Rally Challenge    

Class
N3 = Current and former FIA Group N cars over 1400cc up to and including 2000cc    
N4 = Current and former FIA Group N cars over 2000cc    
B10 = Over 1400cc up to and including 1600cc inclding all FIA R2B Cars    
B11 = Over 1600cc up to and including 2000cc    
B12 = Over 2000cc two wheel drive    
B13 = Over 2000cc four wheel drive cars that do not qualify for Class N4 or WR1 and FIA R4 cars    
B14 = Current and former World Rally Cars with a sequential gearbox, plus current and former S2000 and R5 cars and any derivatives therefrom.    
H1 = All Historic category 1 cars and Category 2 and 3 cars up to 1600cc and Category 4 cars upto 1400cc    
H2 = Historic Category 2 and Category 3 cars with single cam engines over 1600cc and Category 4 cars up to 1600cc    
H3 = Historic Category 2 and Category 3 cars with multi cam engines over 1600cc and category 4 cars over 1600cc    
1400C = - Cars up to 1400cc with:- (a) 8 valve engines (b) Engines with more than 8 valves that retain the standard fuel and inlet manifold systems (c) Engines up to 1000cc not eligible for the BTRDA RF1.0 class(d) Current and former FIA Gp N1 cars.    
1400S = All other cars up to and including 1400cc.    
RF1.4 = BTRDA Rally First cars over 1000cc up to and including 1400cc    
RF1.6 = BTRDA Rally First cars over 1400cc up to and including 1600cc