d parallel time systems TDT and TDB
   are seconds measured in those respective systems. So clock rates may be
   TDT or TDB seconds per most significant clock count. For example, for
   the GLL orbiter spacecraft clock, the rate unit is ``TDB seconds per
   RIM.''
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   The specific method by which pairs of time values and rates are used to
   map encoded SCLK to parallel time values is explained in detail below.
   In the following discussion we'll use the name ``PARSYS'' to refer to
   the parallel ti