m is a number in the range from 1 to f, wherein f is the total number of {HEAD ~ isocyanate groups} per {TAIL ~ molecule} of isocyanate compound; and 
per
m is a number in the range from 1 to f , wherein f is the total number of { HEAD ~ isocyanate groups } per { TAIL ~ molecule } of isocyanate compound ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH