In one embodiment, {HEAD ~ reference data} could be provided by {TAIL ~ the taxi navigation database} 142 
provided by
In one embodiment , { HEAD ~ reference data } could be provided by { TAIL ~ the taxi navigation database } 142
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH