The background program operates in a selected one of several possible modes, one of which waits for {HEAD ~ data} to supplied from {TAIL ~ an external data acquisition instrument} before returning control to the foreground process so that the two processes can operate in synchronism 
to supplied from
The background program operates in a selected one of several possible modes , one of which waits for { HEAD ~ data } to supplied from { TAIL ~ an external data acquisition instrument } before returning control to the foreground process so that the two processes can operate in synchronism
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH