Calibration of the system is provided by means for an operator to specify tone densities for the second medium that correlate to signal levels derived from {HEAD ~ the first medium} for {TAIL ~ each channel} 
for
Calibration of the system is provided by means for an operator to specify tone densities for the second medium that correlate to signal levels derived from { HEAD ~ the first medium } for { TAIL ~ each channel }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL