I'm curious how the class names for steam engines came about, specifically for the C&O. I know all the nicknames for the different wheel configurations (Mountain for 4-8-2, Mikado for 2-8-2, etc.) But most of the class names (such as H8 type 2-6-6-6's, and J3 type 4-8-4's) escape me. Is there a website with information about what the class name and number signify? Thanks!