A signal having a predetermined pattern is written in {HEAD ~ a predetermined region} of {TAIL ~ an optical disc} at a plurality of different write power levels Pwm 
of
A signal having a predetermined pattern is written in { HEAD ~ a predetermined region } of { TAIL ~ an optical disc } at a plurality of different write power levels Pwm
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH