In an embodiment, region 38 has a depth essentially equal to {HEAD ~ the depth} of {TAIL ~ region} 34 
of
In an embodiment , region 38 has a depth essentially equal to { HEAD ~ the depth } of { TAIL ~ region } 34
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH