Examining FIG 6 in more detail, this figure is a simplified line representation of {HEAD ~ the front} of {TAIL ~ a users} head 200 as seen from the top 
Examining FIG 6 in more detail , this figure is a simplified line representation of { HEAD ~ the front } of { TAIL ~ a users } head 200 as seen from the top
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH