An original or model after which anything is copied; the pattern of anything to be engraved, or otherwise copied, cast, or the like; a primary form; exemplar; archetype.
Prototype has several meanings, but typically refers to real-world trains (in contrast to scale models of them) and equipment. Also called 12"-to-the-foot. However, it can also mean the first item in a series, which meaning is often applied to equipment built as tests by real railroads. RERAIL FROG A rerail-frog is a kind of a metal ramp thing that is used to help re-rail a car or engine that has gone off the track but not wandered too far away or overturned. It is temporarily spiked, wedged or clamped next to the rail at the wheel that needs to be lifted back over the rail and then the car is pushed or pulled by the engine to get the wheel to ride up over the ramp and back onto the track. Typically in branch line service you would see these dangling from the sides of the tender along with some chains or cables. More tools including jacks, levers, wrenches for splice bolts and so on might be kept in the caboose or stashed on the engine.