The filter object used to screen nodes. Filters are applied to
 further reduce (and restructure) the NodeIterator's view of the
 document. In our case, we will be using hardcoded filters built
 into our iterators... but getFilter() is part of the DOM's 
 NodeIterator interface, so we have to support it.<DD><DL>
<DT><B>Specified by: </B><DD><A HREF="../../../org/w3c/dom/traversal/NodeIterator.html#getFilter()">getFilter</A> in interface <A HREF="../../../org/w3c/dom/traversal/NodeIterator.html">NodeIterator<