{HEAD ~ The method,1}, wherein {TAIL ~ said difference count} and said pulse count are stored separately on the occurrence of a pulse of said second series in first and second storage means, respectively 
wherein
{ HEAD ~ The method,1 } , wherein { TAIL ~ said difference count } and said pulse count are stored separately on the occurrence of a pulse of said second series in first and second storage means , respectively
HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH