title: HTML5 appcache manifest file extension
body: <p>I read this line from <a href="http://html5boilerplate.com" rel="noreferrer"> HTML5 Boilerplate </a> :</p>
  
  <pre>
  HTML Manifest files now use .appcache extension instead of .manifest, 
  as per http://html5.org/r/5812.
  </pre>
  
  <p>And I saw this from <a href="http://html5.org/r/5812" rel="noreferrer">http://html5.org/r/5812</a></p>
  
  <pre>
  Change the suggested extension for appcache manifests from .manifest to .appcache 
  to avoid clashing with Microsoft's unregistered application/manifest type
  </pre>
  
  <p>Here is my question. What is <strong>Microsoft's unregistered application/manifest type</strong> and when does it clash?</p>