XML Validation

**KoOL** · **XML Validation -** 01-10-2008, 07:58 AM

XML with correct syntax is Well Formed XML.
XML validated against a DTD is Valid XML.
Well Formed XML Documents

A "Well Formed" XML document has correct XML syntax.
A "Well Formed" XML document is a document that conforms to the XML syntax rules that were described in the previous chapters:

XML documents must have a root element
XML elements must have a closing tag
XML tags are case sensitive
XML elements must be properly nested
XML attribute values must always be quoted

<?xml version="1.0" encoding="ISO-8859-1"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
Valid XML Documents

A "Valid" XML document also conforms to a DTD.
A "Valid" XML document is a "Well Formed" XML document, which also conforms to the rules of a Document Type Definition (DTD):
<?xml version="1.0" encoding="ISO-8859-1"?>
<!DOCTYPE note SYSTEM "InternalNote.dtd">
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>
XML DTD

A DTD defines the legal elements of an XML document.
The purpose of a DTD is to define the legal building blocks of an XML document. It defines the document structure with a list of legal elements.
XML Schema

XML Schema is an XML based alternative to DTD.