The value of an element node is the text of the node
The value of an attribute node is the attribute value
The value of a text node is the text of the node
The value of a CDATA section node is the text of the section
The value of an entity reference node is null
The value of an entity node is null
The value of a processing instruction node is the content of the processing instruction, not including the target
The value of a comment node is the text of the comment
The value of a document node is null
The value of a document type declaration node is null
The value of a document fragment node is null
The value of a notation node is null