Description

   The Compare Midpoint Times routine compares two binary timestamps
   and returns a flag indicating that the first timestamp is greater
   than, less than, or equal to the second timestamp. Inaccuracy
   information is ignored for this comparison; the input values
   are, therefore, equivalent to the midpoints of the time intervals
   described by the input binary timestamps.

   The input binary timestamps express two absolute or two relative
   times. Do not compare relative binary timestamps and binary
   timestamps. If you do, no meaningful results and no errors are
   returned.

   The following routine does a lexical ordering on the time
   interval midpoints.

   utc1 is utc_lessThan utc2 iff
           utc1.time < utc2.time

   utc1 is utc_greaterThan utc2 iff
           utc1.time > utc2.time

   utc1 is utc_equalTo utc2 iff
           utc1.time == utc2.time