>>1133123>Whyte system is by far the most dominant and commonly used form. For steam locos at least. UIC (or it's simplified US version) is preferred for diesels.
And to be honest, UIC is a better system (in which numbers are undriven axles, and letters are driven) is a better system for some locomotives.
Pic related, for example, cannot be classified really under Whyte. You couldn't say "0-4-0+2-2-0" because it's a single coupled set of drivers. While the UIC version, "B2A," still doesn't tell you that they're coupled,. it's still better.
As for other UIC examples:
4-4-0 = 2'B
2-10-0 = 2'E
4-8-0 = 2'D
2-8-8-2 = (1'D)D1 Parenthesis indicates articulated
