In {TAIL ~ the preferred embodiment}, {HEAD ~ reference terrain altitude maps} are converted to reference map transformation values 
In
In { TAIL ~ the preferred embodiment } , { HEAD ~ reference terrain altitude maps } are converted to reference map transformation values
REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH