Basic Operation
3.
Probe Compensation: Voltage probe compensation output and ground, used to electrically 
match the probe to the oscilloscope input circuit. The probe compensation ground and BNC 
shields   connect   to   earth   ground   and   are   considered   to   be   ground   terminals.   To   avoid 
damages, do not connect a voltage source to any of these ground terminals.
DSO5000 Series Digital Storage Oscilloscope User Manual                                            49