What is the objective of "Auto On/Off" command for setting DC Bias ranging mode of the E4980A via GPIB?

When measuring a device whose characteristic is sensitive to DC bias voltage transience, DC bias range needs to be fixed in order to avoid transient discontinuation of bias output voltage due to a bias voltage range shift. The "Auto On/Off" command enables the bias voltage range to be fixed at +/-40 V range (when Auto Off command is executed). DC bias voltage can be varied from 0 V to +/-40 V with a constant 5 mV resolution at the fixed 40 V range. This GPIB command is available with Firmware Revision 2.10 and later.