Canadian National
description of classes
First letter = builder
CFA-16a = Canadian Locomotive Company
EF-644zf = General Electric and Wabtec
GPA-430a = General Motors and Progress Rail
LR-7a = Miscellaneous
MS-7c = Montreal Locomotive Works, ALCO, and Bombardier
Second letter = type of work
EF-439a = Freight
GH-00c = Hump
MPA-18a = Passenger
CR-16a = Road Switcher
LS-3a = Switcher
GY-9a = Yard
Third letter (if present) = configuration
CPA-16a = Cab unit
GPB-17b = Cabless unit
MRE-18g = Electric generator fitted
GRG-17e = Steam generator fitted
MHL-410a = Leading unit
MHT-410a = Trailing unit
First Number (if three digits) = number of axles
GR-420-a = 4 axles
EF-640b = 6 axles
Remaining Numbers = horse power in 100s rounded up to nearest 100
CRG-24a = 2,400 hp
GPA-430a = 3,000 hp
EF-644zf = 4,400 hp
MS-7a = 700 hp
Lowercase letters = sub-class
GPA-430a = first sub class in GPA-430
GPA-430b = second sub class in GPA-430
GPA-430c = third sub class in GPA-430
and so on
NOTE: in most cases the letters i and o are not used