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