title: What is the purpose of RegisterGlobalFilters?
body: <p>In MVC3, I have CustomErrors enabled this way:</p>
  
  <pre><code>&lt;customErrors mode="On" defaultRedirect="/Error/Generic"/&gt;
  </code></pre>
  
  <p>And It works whatever I add or not the <code>HandleErrorAttribute</code> to the <code>GlobalFilterCollection</code> filters. </p>
  
  <p>In <code>void Application_Start()</code>, it does not change anything if I comment out this line
  <code>RegisterGlobalFilters (GlobalFilters.Filters);</code></p>
  
  <p>What is the real purpose of this call to <code>RegisterGlobalFilters</code>?</p>