HP 54710A User's Reference Manual page 106

Calibrate to best accuracy
Calibrate to best accuracy allows you to achieve the one percent accuracy
specifications. A best accuracy calibration is valid for a specific plug-in, in a
specific slot, in a specific mainframe. It is valid as long as the current
temperature ∆ and plug-in best accuracy temperature ∆ are within ±5
degrees, and no more than 24 hours has elapsed since the best accuracy
calibration was performed.
The calibration factors for a best accuracy calibration are stored in the
mainframe's memory. The calibration factors are retained until another best
accuracy calibration is performed in this slot.
If you perform another best accuracy calibration on that plug-in in a different
slot or mainframe, when you bring the plug-in back into the original slot, and
as long as another best accuracy calibration was not performed in that slot,
the original best accuracy calibration factors are retained.
The best accuracy calibration factors for a two-wide plug-in are stored in the
left slot. For example, if you performed a best accuracy calibration on a
two-wide plug-in in slots 2 and 3, the best accuracy calibration factors are
stored in the memory behind slot two. You can remove the two-wide plug-in
and install a single-wide plug-in in slot 3. You can perform a best accuracy
calibration on the single-wide plug-in in slot 3 without affecting the best
accuracy calibration factors for the two-wide plug-in that are stored behind
slot 2.
Also, there is a best cal protect switch on the rear panel of the oscilloscope.
The normal setting for this switch is unprotected so that you can perform a
best accuracy calibration at any time without having to access the rear panel
of the oscilloscope.
To perform a best accuracy calibration
Press the Calibrate to best accuracy softkey. Then, follow the instructions on
the display.
Channel Menu
Calibrate
6–11