ne, or aborting execution of the program.
    </p>

    <p>
      Most users never encounter <b>XERROR</b> directly.  However,
      they may receive warnings and other error messages produced
      by <b>XERROR</b>, if the software they are calling has encountered
      an error condition and uses <b>XERROR</b> to report and
      handle the problem.
    </p>

    <p>
      An experienced user or software developer may wish to incorporate
      <b>XERROR</b> into software being developed, or to modify the
