calculating {TAIL ~ an optimum write power compensation value PcO} by using {HEAD ~ the evaluated value} Mm× 
calculating { TAIL ~ an optimum write power compensation value PcO } by using { HEAD ~ the evaluated value } Mm×
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH