​x
 
<!DOCTYPE message[ -> Root element of the document is &ldquo;message&rdquo;.
<!ELEMENT message (to,from,sub,body)> -> Element &ldquo;message&rdquo; has to, from, sub, body elements.
<!ELEMENT to (#PCDATA)> -> &lsquo;to&rsquo; is element which takes only &lsquo;parsed character&rsquo; data.
<!ENTITY from "From: Common Man"> -> &lsquo;from&rsquo; is shortcut to &lsquo;From: Common Man&rsquo;
<!ELEMENT sub (ANY)> -> &lsquo;sub&rsquo; element takes any kind of parsable data.
​
<?xml version="1.0"?>
<!DOCTYPE message[
<!ELEMENT message (to,from,sub,body)>
<!ELEMENT to (#PCDATA)>
<!ENTITY from "From: Common Man">
<!ELEMENT sub (ANY)>
]>
<message>
    <to>President</to>
    <from>&from;</from>
    <sub>Congratulations on becoming president!</sub>
    <body>Congratulations!Celebrating our independence in your rule!!</body>
</message>