I used to have one of those side of the bellows scales but I think it fell off and found it's way into the recycling bin.
However if you are using a cold light head it is a moot point. You are supposed to keep the top bellows collapsed.
I do generally keep my top bellows open a bit, maybe an inch or two so that the cold light doesn't sit so close to the film.
When printing 4x5 you have to collapse the top bellows all the way but with roll film you can back it off a bit like I do.
Dennis