Upon {HEAD ~ detection} of a trigger, such as the exceeding of an error threshold or {TAIL ~ the direction} of a user, a diagnostic link system enters a diagnostic information transmission mode 
Upon { HEAD ~ detection } of a trigger , such as the exceeding of an error threshold or { TAIL ~ the direction } of a user , a diagnostic link system enters a diagnostic information transmission mode
OTH 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH