Substantially accurate calibration of {HEAD ~ output impedance} of a device under test to within {TAIL ~ a predetermined range} of allowable impedance 
Substantially accurate calibration of { HEAD ~ output impedance } of a device under test to within { TAIL ~ a predetermined range } of allowable impedance
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH