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) 2000 World Wide Web Consortium,
 * (Massachusetts Institute of Technology, Institut National de
 * Recherche en Informatique et en Automatique, Keio University). All
 * Rights Reserved. This program is distributed under the W3C's Software
 * Intellectual Property License. This program is distributed 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.
 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
 */

package org.w3c.dom.css;


 The CSSRuleList interface provides the abstraction of an 
ordered collection of CSS rules. 

 The items in the CSSRuleList are accessible via an 
integral index, starting from 0. 

See also the Document Object Model (DOM) Level 2 Style Specification.

Since:DOM Level 2
/**
 *  The <code>CSSRuleList</code> interface provides the abstraction of an 
 * ordered collection of CSS rules. 
 * <p> The items in the <code>CSSRuleList</code> are accessible via an 
 * integral index, starting from 0. 
 * <p>See also the <a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113'>Document Object Model (DOM) Level 2 Style Specification</a>.
 * @since DOM Level 2
 */
public interface CSSRuleList {
    
 The number of CSSRules in the list. The range of valid 
child rule indices is 0 to length-1 
inclusive. 

/**
     *  The number of <code>CSSRules</code> in the list. The range of valid 
     * child rule indices is <code>0</code> to <code>length-1</code> 
     * inclusive. 
     */
    public int getLength();

    
 Used to retrieve a CSS rule by ordinal index. The order in this 
collection represents the order of the rules in the CSS style sheet. 
If index is greater than or equal to the number of rules in the list, 
this returns null. 

Params:
  • index – Index into the collection
Returns:The style rule at the index position in the 
  CSSRuleList, or null if that is not a 
  valid index.
/**
     *  Used to retrieve a CSS rule by ordinal index. The order in this 
     * collection represents the order of the rules in the CSS style sheet. 
     * If index is greater than or equal to the number of rules in the list, 
     * this returns <code>null</code>. 
     * @param index Index into the collection
     * @return The style rule at the <code>index</code> position in the 
     *   <code>CSSRuleList</code>, or <code>null</code> if that is not a 
     *   valid index. 
     */
    public CSSRule item(int index);

}