The cutting edges of {TAIL ~ the reamer sections} are {HEAD ~ parallel straight cutting edges} or helical cutting edges 
The cutting edges of { TAIL ~ the reamer sections } are { HEAD ~ parallel straight cutting edges } or helical cutting edges
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH