Fuel portal indicators

Hi All
Anybody who can explain the Green circles on the Fuel tanks ?
second, Feed is shown in left and right, why ?

Thanks
Frank

Hi All
Anybody who can explain the Green circles on the Fuel tanks ?

Probably represents the Fuel tanks currently selected and being used?

So "B" could be a synonym for "Isolate" ?

So "B" could be a synonym for "Isolate" ?

I don't know.
Even what I said in my last post is speculation on my part.