On ammeter specifications it is often written accuracy specification
$$ (….\% rdg+ … digits) $$
While the ammeter can have a certain last digit on the screen, which determine the resolution if the instrument
My question is : is the error expressed in the specification really just an offset (i.e. a constant shift on the current) for all the measurements made with the ammeter?
In other words is it just a systematic error?
Or is it actually something more than just an offset?
I mean, if it was just a constant offset, then its value could be provided to correct all measurements and there would not be need of this error at all!