Upon identifying {HEAD ~ the presence} of {TAIL ~ the television commercial}, the television commercial detector provides an indication of the presence of the television commercial to direct further processing of the television commercial 
of
Upon identifying { HEAD ~ the presence } of { TAIL ~ the television commercial } , the television commercial detector provides an indication of the presence of the television commercial to direct further processing of the television commercial
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH