Martel Electronics 135 - Manual (Page 33)

Exit the Setup menu.
The 130 will display the input in % ERR and the output in % Scale on exit
from the setup menu.
The 135 will now display in the previously selected Engineering Units.
To display the % Error press the % Key. Press the % Key again to return
to the Engineering Unit display.
Once the calibrator is turned off, all % Error setups are lost.
Operation
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Enter output F.S.
EngUnits ???????