title: What does Etc mean in time zone definitions
body: <p>I can't believe this hasn't been asked before, but I can't find it on SE — or even on the googletron.</p>
  
  <p>What does "Etc" mean in time zone definitions?</p>
  
  <p>Example: php's</p>
  
  <pre><code>date_default_timezone_set('Etc/GMT');
  </code></pre>