Yellow Dot Clue for Aero Ektar Aficionados

Put this post in the arcane category: You have to be one of the possessed people who have latched onto the Kodak Aero Ektar and other big eyes to appreciate the meaning of this. Here is a plate for a very large aero lens, a giant 48 inch f6.3 mass of glass too heavy to even lift.

But the label with its dot is interesting. If you read it normally, left to right, it almost looks like you could read it as "48 inch f/6.3 for 9 inch X 18 inch camera telephoto type I-class B DAY NIGHT temperature compensated USAF spec No..."

Notice that the dark dot is violet or purple. The two in this context seem to me to indicate the use of the lens, in this case day and night. Sunny/Cloudy? I don't think so, and cannot come up with another plausible interpretation of the dots.

Therefore, the famous yellow dot, so cherished by those who pay extra for it in their Aero Ektar hoods, might indicate "Daylight Use".  What would be different from night use? In darkness, the Aero Ektar was used with flash bombs to illuminate the scene of night bombings.

Do we now know that the yellow dot means? Comments please.

I grabbed this image and cropped it, taken from some other online post that I cannot find, to provide a proper attribution, at the moment. Here is another Aero Ektar and some earlier speculations about the meaning of the dot.