List of SNCF classes

Multiple units are numbered the same as locomotives, but prefixed by X for DMUs or Z for EMUs.

A now discontinued practice was to prefix the class number by the wheel arrangement.

SNCF's adaptations included using the axle arrangement in full, and reversing the class letters of tank locomotives.

Others railways' designs taken over after World War II were usually given the letter U (American), W (British), X, Y, or Z (German).

Where locomotives were upgraded or rebuilt, the class letter changed, but not the number.