Therefore, the optical discs of {TAIL ~ two kinds} in which {HEAD ~ the recording layers} are placed at different distances can precisely be recorded or reproduced, respectively 
in
Therefore , the optical discs of { TAIL ~ two kinds } in which { HEAD ~ the recording layers } are placed at different distances can precisely be recorded or reproduced , respectively
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL REL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH