{HEAD ~ The largest distance} of any focus point from the best fit surface is then identified and compared to {TAIL ~ a predetermined maximum distance value} 
is compared to
{ HEAD ~ The largest distance } of any focus point from the best fit surface is then identified and compared to { TAIL ~ a predetermined maximum distance value }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH REL OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL