TUN</b> reports the first unit number of the files receiving error messages.
        </li>
        <li>
          <b>XSETF</b> sets the error control flag.
        </li>
        <li>
          <b>XSETUA</b> sets the unit numbers of the files receiving error messages.
        </li>
        <li>
          <b>XSETUN</b> sets the unit number of the main error output file.
        </li>
      </ul>
    </p>

    <p>
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