title: where is $content variable declared in Yii?
body: <p>I am using Yii Framework. In the view, main.php, there is a reference to the $content block</p>
  
  <pre><code>&lt;?php echo $content; ?&gt;
  </code></pre>
  
  <p>I could not find it anywhere in the model or elsewhere in the demo project. Can someone shed light on this? Or may be this variable is never declared? I have not modified the demo project yet.</p>