said first timer being adapted to periodically establish the commencement of {HEAD ~ a system} on {TAIL ~ time}; and 
on
said first timer being adapted to periodically establish the commencement of { HEAD ~ a system } on { TAIL ~ time } ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH