Metaproxy XML configuration snippets can be reused by other filters using the XInclude standard, as seen in the /etc/config-sru-to-z3950.xml example SRU configuration.

    <filter id="sru" type="sru_z3950">
      <database name="Default">
       <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
                    href="explain.xml"/>
      </database>
    </filter>