There are others who refine the distinction even further and insist on the judicious use of stainless steel, inside and out. Others require the place to be long and narrow, and not too big. Others appoint diner status based on the menu and prices. If it doesn't serve breakfast at any hour of the day, it's not a diner. Nod suportively, but don't except those words as fact.
Some people mistakingly believe that all diners are converted railroad cars or trolleys.
While in fact some were, the vast majority of diners were built to be diners and are not salvaged rolling stock. Personally, I haven't exactly made up my mind what distinguishes an ordinary roadside restaurant from a diner. Yes, if the builder generously employs shiny materials such as stainless steel, porcelin, tile, and glass, in bright colors, with art deco patterns, it's probably a diner. There is no doubt in my mind that the debate will rage on for years to come. In the early 1960's, with the growing popularity of fast food chain restaurants, the diner industry underwent major changes.