I have a GWInstek GDM-8255A 199999 count Multimeter. The user manual and specification sheet list ranges of 100mV, 1V, 10V, 100, 1000V, but it is actually 200mV, 2V, 20V, 200V, 1000V. The question is, what calibration points should be used for calibration? I say full scale, the calibration lab said , we use 10mV, 1V, 10V, 100V, 1000V. Any comments from professional calibration technicians? UNI-T also has a 199999 count, 5 1/2 DMM, UT805A , they document the ranges as, 200mV, 2V, 20V, 200V, 1000V.
Update: I asked this lab to measure the DC input resistance of the meter at 100mV, 1V, 10V, 100V, 1000V for some high accuracy voltage dividers I need. They said they are strictly prohibited from making those measurements, or they will return the meter to me. I said ok, you are the experts.