XML file for a simple note (n.b. reference to a ruleset file):
<?xml version="1.0"?> <!DOCTYPE note SYSTEM "simple_note.dtd"> <note> <to>Tove</to> <from>Jani</from> <heading>Reminder</heading> <body>Don't forget me this weekend!</body> </note>
Ruleset file specifying what elements are allowed where in a note:
<!ELEMENT note (to,from,heading,body)> <!ELEMENT to (#PCDATA)> <!ELEMENT from (#PCDATA)> <!ELEMENT heading (#PCDATA)> <!ELEMENT body (#PCDATA)>
Example based on http://w3schools.com/dtd/dtd_intro.asp