sing
<a class="reference external" href="https://en.wikipedia.org/wiki/Backus%E2%80%93Naur_form">BNF</a> notation with
the regular extensions, is the following:</p>
<pre>
<strong id="grammar-token-depfile">depfile      </strong> ::=  <a class="reference internal" href="#grammar-token-rule"><code class="xref docutils literal notranslate"><span class="pre">rule</span></code></a>*
<strong id="grammar-token-rule">rule         </strong> ::=  <a class="reference internal" href="#grammar-token-targets"><code class