{HEAD ~ a user interface} for receiving {TAIL ~ user input} to enable tracking wherein the user input is received via a user interface that enables the user to manually enable tracking, to disable tracking or enable automatic triggering of tracking 
for receiving
{ HEAD ~ a user interface } for receiving { TAIL ~ user input } to enable tracking wherein the user input is received via a user interface that enables the user to manually enable tracking , to disable tracking or enable automatic triggering of tracking
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL 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 OTH OTH OTH OTH OTH