symbols "#@+" in PHP comments
<p>I have found some special symbols "#@+" and "#@-" in the comments/documentation in ZF1. Example:</p>

<pre><code>/**#@+
 * @access protected
 */
</code></pre>

<p>(<a href="https://github.com/zendframework/zf1/blob/master/library/Zend/Mail.php#L54" rel="nofollow">https://github.com/zendframework/zf1/blob/master/library/Zend/Mail.php#L54</a>)</p>

<p>I have seen before in another different repositories.</p>

<p>What do these mean?</p>