The apparatus 17, wherein the program code is configured to identify {TAIL ~ a set} of {HEAD ~ values} that potentially satisfy the query by: 
The apparatus 17 , wherein the program code is configured to identify { TAIL ~ a set } of { HEAD ~ values } that potentially satisfy the query by :
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH