the reason that i asked was following.
when you have a BL pup, bought secondhand and you have the idea that the writing on it is not right, ore the sticky is gone than there is no other mark to check than the Henry mark BL labels his pups with.
measuring resistance only helps finding out if the pup works.
i sometimes think that my l500R is stronger than my XL.
(i understand that strings move more at neck and so make more output.)