title: including xml file in another xml file
body: <p>In PHP, it's possible to include 1 php file in another php.</p>
  
  <p>Is there something similar for xml files. </p>
  
  <p>The xml file is a database schema (for Propel), and some tables I plan to use in more than one project. I'd prefer to create 1 xml file and include when needed. </p>