This provides, for example, the ability to analyze Web activity by efficiently grouping and analyzing {HEAD ~ data} across {TAIL ~ several independent dimensions} 
This provides , for example , the ability to analyze Web activity by efficiently grouping and analyzing { HEAD ~ data } across { TAIL ~ several independent dimensions }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL