Tektronix P6245 Manuel D'utilisation page 188

Performance Verification
10. Measure and record the multimeter reading as M2.
NOTE. If you are unable to set the power supply precisely, record the
actual readings and determine the absolute difference.
|Vmax - - Vmin| = difference.
Divide the difference by 10 to account for the probe's ideal
attenuation factor. For example: 0.4 is the difference between +2 and
- - 2, divided by 10.
11. Determine the percent error by using the formula below:
%Error = [ M1 − M2
The calculated error should be ≤2%.
NOTE. An unaccceptable error value may result if a low tolerance
termination is substituted for the recommended termination.
4- 8
− 1] × 100%
0.4
P6245 Instruction Manual