{HEAD ~ The processing unit} receives a query for an item and uses {TAIL ~ the features index} to determine search results including the item, such as a location and a time of the item 
{ HEAD ~ The processing unit } receives a query for an item and uses { TAIL ~ the features index } to determine search results including the item , such as a location and a time of the item
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH 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