Marker lights on front of covered wagon A units

[Nieuweboer]

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I want to illuminate the small lights just above the number shields on the nose of A unit covered wagons ( EMD F and Alco FA). I looked at a lot of color pictures to find out what color these lights are, but on all pictures they appear to be either colorless (translucent) or silvery opaque.I assume they are a sort of tail lights when the locomotive is backing up but I'm not sure.Can anyone give me details on the function and colors of these lights.

[Adelie]

Those are actually classification lights (I think that is the correct term). Usually, they are not illuminated, which means it is a scheduled train. If they are illuminated white, it is an "extra." If illuminated green, there is at least one more section following this section. When the locomotive is on the rear of the train they are illuminated red and used as markers. This would be cases such as a pusher or a commuter train with a locomotive on only one end and it is on the rear.

[jimrice4449]

Adelie puts it sucincly and accurately. Their use might depend on the era you're modeling. When CTC (Centralized Traffic Control) was in place the green would not be used as much as when timetable/train order operation was being used since most frieght trains would be run as extras, using the white class lights, and only psgr trains were scheduled and generally didn't run in sections, eliminating the need for green class lights

[johncolley]

Back in the good ol' days ('50's) The markers would be red if on the back of a pushing helper against a steel caboose, except if the caboose was wood it would have to be placed behind the loco so the markers would be on the caboose.