<b>XERBLA</b> is an error handler for the Level 2 and Level 3 BLAS routines.
        </li>
        <li>
          <b>XERCLR</b> resets the most recent error number to 0.
        </li>
        <li>
          <b>XERCNT</b> allows user control over the handling of errors.
        </li>
        <li>
          <b>XERCTL</b> allows the user control over individual errors.
        </li>
        <li>
          <b>XERDMP</b> prints the error tables and then clears them.
        </li>
        <li>
          <b>XERHLT