Does anybody know what the yellow dot on some Wollensak lenses signifies? I've heard that it means the lens is coated, but I have a 15" Tele-Optar with the yellow dot that does not look coated to me.
Maybe the yellow dot was used for early coated lenses that are only coated on the inside surfaces due to the softness of early coatings?

all of the 'dotted' lenses I've seen were coated. the same is true for the "W inside the C" logo.

I've also seen yellow dots, blue dots, and "yellow and blue dots"

Before I start quoting Dr. Suess and somebody "Puts me in the Zoo" I'll just say, I have yet to figure out what each variation meant.