idle curiosity Heligon I.D.

It just means that the lens is coated. Different makers used different markings for their coated lenses. Zeiss still use their red "T" or "T*", Schneider used a red triangle, Steinheil used "VL" and Agfa a red ring with a dot in the middle.

Not sure what the red "A" is supposed to stand for, though. Maybe "Antireflex-" something.
 
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