Objects implementing the NamedNodeMap interface represent collections of nodes that can be accessed by name. NamedNodeMap does not inherit from NodeList.
NamedNodeMaps are not maintained in any particular order. Objects contained in an object implementing NamedNodeMap may also be accessed by an ordinal index, but this is simply to allow convenient enumeration of the contents of a NamedNodeMap and does not imply that the DOM specifies an order to these Nodes.