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