Echo nested XML to the console or a file. Since Apache Ant 1.7
| Attribute | Description | Required | 
| file | The file to receive the XML. If omitted nested XML will be echoed to the log. | No | 
| append | Whether to append file, if specified. | No | 
| namespacePolicy | Sets the namespace policy as defined
      by org.apache.tools.ant.util.DOMElementWriter.XmlNamespacePolicy.
      Valid values areignore,elementsOnly, orall.
      Since Apache Ant 1.8 | No, default ignore | 
<echoxml file="subbuild.xml">
  <project default="foo">
    <target name="foo">
      <echo>foo</echo>
    </target>
  </project>
</echoxml>
Creates an Ant buildfile, subbuild.xml.