title: PHP variable for timezone
body: <p>I'm asking about PHP contants for timezones name  </p>
  
  <p><strong>For Example :</strong></p>
  
  <pre><code>$rc = date_default_timezone_set("US/Mountain");
  </code></pre>
  
  <p><code>"US/Mountain"</code> to be constants not write it as text </p>
  
  <p>is it exist from PHP classes or I need to do it myself</p>
  
  <p>Thanks in advance </p>