HP 54710A User's Reference Manual page 45

How the Oscilloscope Works
System Bandwidth
To have a flat frequency response, the voltage divider must be compensated
for the capacitance of the cable and the oscilloscope or logic analyzer's input
capacitance. One of the compensating capacitors is made adjustable so you
can optimize the step response flatness because the input capacitance of the
oscilloscope is unknown. The HP 54720A provides a square wave at the
calibrator output for this purpose.
Figure 1-12
Compensated passive divider probe
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