In {TAIL ~ related embodiments} of the invention, {HEAD ~ at least one recessed region} is positioned at a magnetic pole 
In { TAIL ~ related embodiments } of the invention , { HEAD ~ at least one recessed region } is positioned at a magnetic pole
REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH