Each symptom is represented by a separate card which can be independently illuminated to indicate {HEAD ~ the existence} of {TAIL ~ that symptom} 
Each symptom is represented by a separate card which can be independently illuminated to indicate { HEAD ~ the existence } of { TAIL ~ that symptom }
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