| 
             | 
          
            DocumentTraversal contains methods that create 
 NodeIterators and TreeWalkers to traverse a 
 node and its children in document order (depth first, pre-order 
 traversal, which is equivalent to the order in which the start tags occur 
 in the text representation of the document).
         | 
| 
             | 
          Filters are objects that know how to "filter out" nodes. | 
| 
             | 
          
            NodeIterators are used to step through a set of nodes, e.g.
         | 
| 
             | 
          
            TreeWalker objects are used to navigate a document tree or 
 subtree using the view of the document defined by their 
 whatToShow flags and filter (if any).
         |