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