The extent of opening of the sectors 12a and 12b and {HEAD ~ the count N} of {TAIL ~ the up down counter} 42 have a pre established relationship 
of
The extent of opening of the sectors 12a and 12b and { HEAD ~ the count N } of { TAIL ~ the up down counter } 42 have a pre established relationship
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 TAIL TAIL OTH OTH OTH OTH OTH OTH