Resources in php are external
<p>From the <a href="http://www.php.net/manual/en/language.types.resource.php" rel="nofollow">PHP documentation for resource type</a></p>

<blockquote>
  <p>A resource is a special variable, holding a <strong>reference to an external</strong>
  resource. </p>
</blockquote>

<p>A statement I have ignored for years. <code>mysql_*</code>, <code>curl_*</code> etc.</p>

<p>Why are they called external?  Is it because they are add-on libraries? What of <code>fopen()</code>?</p>
