"Green lenses on the marker lamp indicate that the train is split into multiple sections, each with its own locomotive but running on the same schedule. If there are green facing lenses or flags on the last car of an individual train, it means that behind it is following another section of the same train. A red facing lens/flag will appear on the last car of the last section."
Interesting....I have never heard of rear markers indicating multiple sections as classification markers do on a locomotive, at least I can't find that in any of my rule books. I suppose it could have been done on some railroads at various points in history, or maybe an eastern practice, but would be confusing in my mind.
In any case, this is from my 1924 DRGW Rule Book, Rule 19, with instructions to display green to the front, sides and rear when clear of main track.
My 1921 C&S Rule Book shows the same.
Mike Ramsey