Document 1, wherein {HEAD ~ said regions} made of magnetic material are spaced by {TAIL ~ magnetically blank portions} 
are spaced by
Document 1 , wherein { HEAD ~ said regions } made of magnetic material are spaced by { TAIL ~ magnetically blank portions }
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL