Valid XML Document

An XML document that complies with a particular schema, in addition to being well-formed, is said to be valid. A “Valid” XML document also conforms to a DTD.

A “Valid” XML document is a “Well Formed” XML document, in addition it also conforms to the rules of a Document Type Definition (DTD):

<?xml version=”1.0″ encoding=”ISO-8859-1″?>
<!DOCTYPE email SYSTEM “emailStructure.dtd”>
<email>
<sender>
      <sender_name>XYZ Kumar</sender_name>
      <sender_email_id>[email protected]</sender_email_id>
</sender>
<recipient>
      <recipient_name>ABC</recipient_name>
      <recipient_email_id>[email protected]</recipient_email_id>
</recipient>
<subject>Hello! how r U</subject>
<message>
      <message_header>Hello dear</message_header>
      <message_body_text>Hello this is Ravish, how are you dear</message_body_text>
      <message_footer>bye!, take care</message_footer>
</message>
</email>