Accuracy spec. interpretation

[Karel]

Hi everybody,

I need to check a DC voltage in the mV range with a Keysight 34461A.
The DC voltages produced by the DUT are: -2, -1, 0, 1 and 2 mV.
The accuracy of the DMM is 0.0065 % of reading plus 0.0035 % of range (100 mV, it's the lowest range available on the DMM).
Unfortunately, 0.0065 % of 100 mV is too much inaccuracy.
Because I'm only interested in the relative accuracy (the step difference between the different output voltages),
may I ignore the accuracy specified for the range and apply only accuracy specified for the reading?
Is my assumption that the accuracy specified for the range is related to DC-offset errors only, wrong?

To give an example:
I measure the values with the output of the DUT at 1 mV and at 0 mV.
Can I assume the accuracy is (0.0065 x 2) percent of the difference of the two measured values?