{HEAD ~ The temple endpiece} is rotated relative to {TAIL ~ the lens} to set the pantoscopic angle 
is rotated relative to
{ HEAD ~ The temple endpiece } is rotated relative to { TAIL ~ the lens } to set the pantoscopic angle
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH