{HEAD ~ The method} 7, wherein {TAIL ~ the center roller} rotates independently of the first edge roller 
wherein
{ HEAD ~ The method } 7 , wherein { TAIL ~ the center roller } rotates independently of the first edge roller
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH