{HEAD ~ Header file} 900 may have definitions of virtual types and values for each virtual type coded in {TAIL ~ a computer program} 
{ HEAD ~ Header file } 900 may have definitions of virtual types and values for each virtual type coded in { TAIL ~ a computer program }
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL