PHP $_REQUEST['do']
<p>I'm a PHP beginner. I don't see the answer to this question in the php manual.</p>

<p>I know what a REQUEST superglobal does, but is 'do' something built into PHP? I found this code in a tutorial...</p>

<pre><code>if (isset($_REQUEST['do']) &amp;&amp; ($_REQUEST['do'] == 'add') ) 
</code></pre>

<p>Does 'do' just mean that the form has been submitted? In the case of information coming from a link...? </p>
