 FALSE, and NULL</a><a class="headerlink" href="#true-false-and-null" title="Permalink to this headline">¶</a></h2>
<p><strong>TRUE</strong>, <strong>FALSE</strong>, and <strong>NULL</strong> keywords should always be fully
uppercase.</p>
<p><strong>INCORRECT</strong>:</p>
<div class="highlight-ci"><div class="highlight"><pre><span></span><span class="k">if</span> <span class="p">(</span><span class="nv">$foo</span> <span class="o">==</span> <span class="k">true</span><span class="p">)</span>
<span class="