The time window is determined by a window timer which is preset with a number corresponding to {HEAD ~ the opening time} of {TAIL ~ the window} 
of
The time window is determined by a window timer which is preset with a number corresponding to { HEAD ~ the opening time } of { TAIL ~ the window }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL