 parallel time system for any given
   spacecraft clock.
<P>
 
   Conversion from TDB to encoded SCLK follows the reverse path: first, TDB
   values are converted, if necessary, to equivalent values in the parallel
   time system; next, those parallel time values are converted to encoded
   SCLK.
<P>
 
   For each type 1 spacecraft clock, encoded SCLK is related to the
   parallel time system for that clock by a piecewise linear function. The
   function is defined by a set of pairs of encoded SCLK values a