http://xml.apache.org/commons/components/external/: xml-commons provides an Apache-hosted set of DOM, SAX, and JAXP interfaces for use in other xml-based projects. Our hope is that we can standardize on both a common version and packaging scheme for these critical XML standards interfaces to make the lives of both our developers and users easier. The External Components portion of xml-commons contains interfaces that are defined by external standards organizations. For DOM, that's the W3C; for SAX it's David Megginson and sax.sourceforge.net; for JAXP it's Sun. 
/*
 * Copyright (c) 2004 World Wide Web Consortium,
 *
 * (Massachusetts Institute of Technology, European Research Consortium for
 * Informatics and Mathematics, Keio University). All Rights Reserved. This
 * work is distributed under the W3C(r) Software License [1] in the hope that
 * it will be useful, but WITHOUT ANY WARRANTY; without even the implied
 * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * [1] http://www.w3.org/Consortium/Legal/2002/copyright-software-20021231
 */

package org.w3c.dom.ls;

import org.w3c.dom.traversal.NodeFilter;


 LSSerializerFilters provide applications the ability to 
examine nodes as they are being serialized and decide what nodes should 
be serialized or not. The LSSerializerFilter interface is 
based on the NodeFilter interface defined in [DOM Level 2 Traversal and      Range]
. 

 Document, DocumentType, 
DocumentFragment, Notation, Entity
, and children of Attr nodes are not passed to the filter. 
The child nodes of an EntityReference node are only passed 
to the filter if the EntityReference node is skipped by the 
method LSParserFilter.acceptNode(). 

 When serializing an Element, the element is passed to the 
filter before any of its attributes are passed to the filter. Namespace 
declaration attributes, and default attributes (except in the case when "
discard-default-content" is set to false), are never passed 
to the filter. 

 The result of any attempt to modify a node passed to a 
LSSerializerFilter is implementation dependent. 

 DOM applications must not raise exceptions in a filter. The effect of 
throwing exceptions from a filter is DOM implementation dependent. 

 For efficiency, a node passed to the filter may not be the same as the 
one that is actually in the tree. And the actual node (node object 
identity) may be reused during the process of filtering and serializing a 
document. 

See also the Document Object Model (DOM) Level 3 Load
and Save Specification.

/**
 *  <code>LSSerializerFilter</code>s provide applications the ability to 
 * examine nodes as they are being serialized and decide what nodes should 
 * be serialized or not. The <code>LSSerializerFilter</code> interface is 
 * based on the <code>NodeFilter</code> interface defined in [<a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113'>DOM Level 2 Traversal and      Range</a>]
 * . 
 * <p> <code>Document</code>, <code>DocumentType</code>, 
 * <code>DocumentFragment</code>, <code>Notation</code>, <code>Entity</code>
 * , and children of <code>Attr</code> nodes are not passed to the filter. 
 * The child nodes of an <code>EntityReference</code> node are only passed 
 * to the filter if the <code>EntityReference</code> node is skipped by the 
 * method <code>LSParserFilter.acceptNode()</code>. 
 * <p> When serializing an <code>Element</code>, the element is passed to the 
 * filter before any of its attributes are passed to the filter. Namespace 
 * declaration attributes, and default attributes (except in the case when "
 * discard-default-content" is set to <code>false</code>), are never passed 
 * to the filter. 
 * <p> The result of any attempt to modify a node passed to a 
 * <code>LSSerializerFilter</code> is implementation dependent. 
 * <p> DOM applications must not raise exceptions in a filter. The effect of 
 * throwing exceptions from a filter is DOM implementation dependent. 
 * <p> For efficiency, a node passed to the filter may not be the same as the 
 * one that is actually in the tree. And the actual node (node object 
 * identity) may be reused during the process of filtering and serializing a 
 * document. 
 * <p>See also the <a href='http://www.w3.org/TR/2004/REC-DOM-Level-3-LS-20040407'>Document Object Model (DOM) Level 3 Load
and Save Specification</a>.
 */
public interface LSSerializerFilter extends NodeFilter {
    
 Tells the LSSerializer what types of nodes to show to the 
filter. If a node is not shown to the filter using this attribute, it 
is automatically serialized. See NodeFilter for 
definition of the constants. The constants SHOW_DOCUMENT
, SHOW_DOCUMENT_TYPE, SHOW_DOCUMENT_FRAGMENT
, SHOW_NOTATION, and SHOW_ENTITY are 
meaningless here, such nodes will never be passed to a 
LSSerializerFilter. 

 Unlike [DOM Level 2 Traversal and      Range]
, the SHOW_ATTRIBUTE constant indicates that the 
Attr nodes are shown and passed to the filter. 

 The constants used here are defined in [DOM Level 2 Traversal and      Range]
. 

/**
     *  Tells the <code>LSSerializer</code> what types of nodes to show to the 
     * filter. If a node is not shown to the filter using this attribute, it 
     * is automatically serialized. See <code>NodeFilter</code> for 
     * definition of the constants. The constants <code>SHOW_DOCUMENT</code>
     * , <code>SHOW_DOCUMENT_TYPE</code>, <code>SHOW_DOCUMENT_FRAGMENT</code>
     * , <code>SHOW_NOTATION</code>, and <code>SHOW_ENTITY</code> are 
     * meaningless here, such nodes will never be passed to a 
     * <code>LSSerializerFilter</code>. 
     * <br> Unlike [<a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113'>DOM Level 2 Traversal and      Range</a>]
     * , the <code>SHOW_ATTRIBUTE</code> constant indicates that the 
     * <code>Attr</code> nodes are shown and passed to the filter. 
     * <br> The constants used here are defined in [<a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Traversal-Range-20001113'>DOM Level 2 Traversal and      Range</a>]
     * . 
     */
    public int getWhatToShow();

}