However, it should also be understood that {HEAD ~ an element} may also have a variable radial height along {TAIL ~ the surface} of the element 
However , it should also be understood that { HEAD ~ an element } may also have a variable radial height along { TAIL ~ the surface } of the element
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH