In {HEAD ~ the areas} of the web above and below the filled region, {TAIL ~ at least some} of the structural elements are encapsulated and most of the interstitial spaces are open 
In { HEAD ~ the areas } of the web above and below the filled region , { TAIL ~ at least some } of the structural elements are encapsulated and most of the interstitial spaces are open
OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH