Applications can't call the protected CreateChildNode method. This method is used internally to create the implementation object for a new child node. 

CreateChildNode creates a new TXMLNode descendant for the specified IDOMNode interface, with this node as the parent. If the node name of the DOM node matches one of the names listed by the ChildNodeClasses property, the corresponding descendant of TXMLNode becomes the implementation class of the new node. Otherwise, the new node is an instance of TXMLNode. 

ADOMNode is the interface for the DOM implementation's version of the node. 

CreateChildNode returns the interface for the newly created child node. 

Create 

ChildNodeClasses 

CreateDOMNode