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