a designating portion configured to receive {TAIL ~ metadata} defined in a range of all time within {HEAD ~ the displayable period}, the metadata including: 
a designating portion configured to receive { TAIL ~ metadata } defined in a range of all time within { HEAD ~ the displayable period } , the metadata including :
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH