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