title: How do you set the cache to expire after modification?
body: <p>I'm using an .htaccess file to set the headers of a website. I want to know how to set the files cache to expire when after a modification has been made on them. Is this possible?</p>
  
  <p>i.e. Will this work?</p>
  
  <pre><code>ExpiresDefault "modification"
  </code></pre>
  
  <p>In other words, I want the cache to stay until the files have been modified from the server.</p>