{HEAD ~ The method} also includes {TAIL ~ the step} of sensing a parameter representative of air flow through the hole 
{ HEAD ~ The method } also includes { TAIL ~ the step } of sensing a parameter representative of air flow through the hole
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH