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