Another algorithm is a time based algorithm which employs a real time clock to establish preset time intervals during which {HEAD ~ each} of {TAIL ~ the access codes} are used 
of
Another algorithm is a time based algorithm which employs a real time clock to establish preset time intervals during which { HEAD ~ each } of { TAIL ~ the access codes } are used
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH