"Absolute measurement error" service allows you to estimate the measurement accuracy considering uncertainty (error) in the absolute value. It's important if you take measurements at the range edge when the error value contributes to the value displayed on the device screen.
To get the value range it'd be enough to enter the estimate of the value under measurement into Value input field and to see the range of possible values taking all of the standardized errors into consideration.
Note: a point is used as a separator of the integer and fractional part.