When {HEAD ~ the temperature} is within {TAIL ~ a normal burning range}, the elapsed time that the temperature remains within such range is stored as a first count whose magnitude is proportional to the accumulation of particulates 
is within
When { HEAD ~ the temperature } is within { TAIL ~ a normal burning range } , the elapsed time that the temperature remains within such range is stored as a first count whose magnitude is proportional to the accumulation of particulates
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH