The content server may then carry out {HEAD ~ the necessary comparisons} to form {TAIL ~ an affinity group} for the game  
to form
The content server may then carry out { HEAD ~ the necessary comparisons } to form { TAIL ~ an affinity group } for the game
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH