 time units and moduli of
   the fields are:
<P>
 
<PRE>
      Field              Time unit              Modulus
      -----     ---------------------------     --------
        1       60 2/3   sec.                   16777215
        2          2/3   sec.  (666 2/3 ms)           91
        3          1/15  sec.  ( 66 2/3 ms)           10
        4          1/120 sec.  (  8 1/3 ms)            8
</PRE>
   Fields 1--4 are known as: ``Real time image count'' (RIM), ``mod 91
   count,'' ``mod 10 count'' or ``re