vily relies on the ProjectHelper
    implementation and doesn't really perform any work of its own.  If
    you have configured Apache Ant to use a ProjectHelper other than Ant's
    default, this task may or may not work.
  </p>

  <p>
    In the common use case where only Ant's default project helper is
    used, it basically works like the 
    <a href="http://ant.apache.org/faq.html#xml-entity-include">Entity
      Includes as explained in the Ant FAQ</a>, as if the imported file was
    contained in th