ns that the clean filter <em>must</em> accept its own output
without modifying it.</p>
</div>
<div class="paragraph">
<p>If a filter <em>must</em> succeed in order to make the stored contents usable,
you can declare that the filter is <code>required</code>, in the configuration:</p>
</div>
<div class="listingblock">
<div class="content">
<pre>[filter "crypt"]
	clean = openssl enc ...
	smudge = openssl enc -d ...
	required</pre>
</div>
</div>
<div class="paragraph">
<p>Sequence "%f" on the fi