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