Under which conditions is my XML document valid?

  1. the document validates the xml formatting rules :
    • 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
    • check everything regarding your XML document syntax with this online validator
  2. the document validates against the DTD !

What are XML data islands?

Data islands are a way to introduce xml data in an HTML document in Internet Explorer only ;-( with the special HTML tag <xml>.
This is very very very probable that you do not want to do that because it will NOT be supported by any other browser
More on XML data islands

XML namespace

Namespaces are usually used to avoid conflicts between tags having the same name but not the same meaning (semantically differents ;-) ).
Example : xmlns:namespace-prefix="namespaceURI"

The CDATA tag

All text in an XML document will be parsed by the parser.
Only text inside a CDATA section will be ignored by the parser.
Example : <!CDATA[ myjavascript code... ]>