calculating {TAIL ~ a certain write power} Pth for which {HEAD ~ the modulation index} is zero by using the optimum write power compensated value PcO; and 
for
calculating { TAIL ~ a certain write power } Pth for which { HEAD ~ the modulation index } is zero by using the optimum write power compensated value PcO ; and
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH REL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH