Well if you look at Jonathan's picture you will see the two red lights on the nose. Those are "class" lights. Short for classification lights. Back in the golden days of railroading the lights signified the superiority of the train. Conrail kept them red for pusher service. No one else uses them anymore.
Did class lights duplicate/replace flags used previously? I know some steam locomotives had class lights on the smokebox sides, but were they able to be rotated to show different colours? What were the different colours for - white for extra, green for second section, or whatever..... I expect someone can correct me or give the correct answers
