Sign.xml file:

<?xml version="1.0" encoding="UTF-8" ?>

<footer>

<author>P C Tejaswi</author>

<book>Karvaalo</book>

</footer>

Main.xml

<?xml version="1.0" standalone="no" ?>

<!DOCTYPE document [

<!ELEMENT document (genre, footer)>

<!ELEMENT genre (#PCDATA)>

<!ELEMENT author (#PCDATA)>

<!ELEMENT book (#PCDATA)>

<!ELEMENT footer (author, book)>

<!ENTITY foot SYSTEM "sign.xml">

]>

<document>

<genre>Non-Fiction</genre>

&foot;

</document>

Output for the example above will be:

<?xml version="1.0" standalone="no" ?>

<!DOCTYPE document (View Source for full doctype...)>

<document>

        <genre>Non-Fiction</genre>

        <author>P C Tejaswi</author>

<book>Karvaalo</book>

</document>