displaying, on a display screen, the single message document according to a conversational view based upon {TAIL ~ a perspective} of the response level of a user within {HEAD ~ the mail thread} 
displaying , on a display screen , the single message document according to a conversational view based upon { TAIL ~ a perspective } of the response level of a user within { HEAD ~ the mail thread }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD