a 
   that is being parsed. This node must be a <code>Document</code> 
   node, a <code>DocumentFragment</code> node, or a node of a type 
   that is allowed as a child of an <code>Element</code> node, e.g. it 
   cannot be an <code>Attribute</code> node.<DD><CODE>action</CODE> - This parameter describes which action should be taken 
   between the new set of nodes being inserted and the existing 
   children of the context node. The set of possible actions is 
   defined in <code>ACTION_TYPES</code> above.