The system can effectuate electronic commerce and interactive advertising at {HEAD ~ the point} of {TAIL ~ sale} 
of
The system can effectuate electronic commerce and interactive advertising at { HEAD ~ the point } of { TAIL ~ sale }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL