[CA11] red and white dots on i70s wind display

[danstanford]

I see these on my new displays in both apparent and true screens but cannot figure out how to use them. Are they showing maximum values or average values?
As a sailor I want to know how to use them and the only thing making sense is that they show maximums in both directions so you can tell if you have been knocked or lifted.
Can you elaborate?

Thanks,
Dan