Computes the difference between two binary timestamps that
    express either an absolute time and a relative time, two relative
    times, or two absolute times.

    Format

      #include <utc.h>

      int utc_subtime(*result, *utc1, *utc2)

         utc_t *result;
         const utc_t *utc1;
         const utc_t *utc2;

1  –  Parameters

    Input

 utc1

    Binary timestamp or relative binary timestamp.

 utc2

    Binary timestamp or relative binary timestamp.

    Output

 result

    Resulting binary timestamp or relative binary timestamp,
    depending on the operation performed:

    o  absolute time - absolute time = relative time

    o  relative time - relative time = relative time

    o  absolute time - relative time = absolute time

    o  relative time - absolute time is undefined. See NOTES.

2  –  Description

    The Subtract Time routine subtracts one binary timestamp
    from another. The resulting timestamp is utc1 minus utc2.
    The inaccuracies of the two input timestamps are combined and
    included in the output timestamp. The TDF in the first timestamp
    is copied to the output.

3  –  Notes

    Although no error is returned, do not use the combination
    relative time - absolute time.

4  –  Returns

     0   Indicates that the routine executed successfully.
    -1   Indicates an invalid time argument or invalid results.

5  –  Example

    See the sample program for the utc_binreltime routine.

6  –  Related Functions

    utc_addtime