French locomotive classification
Under the French classification system for locomotive wheel arrangements, the system is slightly different for steam and electric/diesel vehicles.
The French system counts axles, rather than wheels. As with Whyte notation, a conventional rigid locomotive will have three digits corresponding to its axle configuration:
The first digit is the number of leading unpowered axles; the second digit the number of powered axles; The third digit the number of trailing unpowered axles.
Electric and diesel
With electric and diesel vehicles include DMUs a letter A-B-C-D replaces 1-2-3-4 for the number of powered axles, and each bogie is grouped separately.
0-4-0+0-4-0 = B-B (if axles connected by rods or other means)
0-6-0+0-6-0 = Co-Co (if axles driven independently)