How are PHP releases numbered?
<p>I am looking to upgrade WordPress on my server. WordPress 3.2 <a href="http://wordpress.org/about/requirements/" rel="nofollow">requires PHP 5.2.4 or greater</a>. My server is running PHP 5.2.17. Looking at the <a href="http://php.net/releases/index.php" rel="nofollow">release history on php.net</a>, I see that: </p>

<ol>
<li>5.2.4 was released 30 August 2007</li>
<li>There is no listing for 5.2.17</li>
<li>5.2.16 was released 16 December 2010</li>
<li>Release order with a few versions goes: 5.2.13, 5.3.2, 5.2.14, 5.3.3, 5.2.15</li>
</ol>

<p>Two questions:</p>

<ul>
<li>What is the logic of this numbering system?</li>
<li>Is PHP 5.2.17 "greater" than 5.2.4?</li>
</ul>
