{HEAD ~ The image data set} may be provided to {TAIL ~ a Head Down Display unit}, a Head Up Display unit, or both, each visual aid is presented on the screen of the display unit 
provided to
{ HEAD ~ The image data set } may be provided to { TAIL ~ a Head Down Display unit } , a Head Up Display unit , or both , each visual aid is presented on the screen of the display unit
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL 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