Under the Whyte notation system, a steam locomotive that has four coupled leading wheels, ten coupled driving wheels, and one pair of trailing wheels.

Under the Whyte notation system, a steam locomotive that has two leading wheels, five pairs of coupled driving wheels, and two trailing wheels.

Under the Whyte notation system, a steam locomotive that has ten coupled driving wheels followed by two trailing wheels, with no leading wheels.

Under the Whyte notation system, a Mallet-type locomotive with two leading wheels on a leading truck, two sets of ten driving wheels, and two trailing wheels on a trailing truck.

(CB slang) Location.

plural of 10-20