Responsive to the condition signal, {HEAD ~ the control part} controls {TAIL ~ the announcing arrangement} at the particular time instant 
Responsive to the condition signal , { HEAD ~ the control part } controls { TAIL ~ the announcing arrangement } at the particular time instant
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH