 a previous attempt and will resume the
download from that position.</p>
</dd>
</dl>
</div>
<div class="paragraph">
<p>If a fatal error occurs, the program writes the error message to
stderr and exits. The caller should expect that a suitable error
message has been printed if the child closes the connection without
completing a valid response for the current command.</p>
</div>
<div class="paragraph">
<p>Additional commands may be supported, as may be determined from
capabilities reported by the helper.</p>