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. 

package org.w3c.dom.svg;

import org.w3c.dom.DOMException;
public interface SVGLength {
  // Length Unit Types
  public static final short SVG_LENGTHTYPE_UNKNOWN    = 0;
  public static final short SVG_LENGTHTYPE_NUMBER     = 1;
  public static final short SVG_LENGTHTYPE_PERCENTAGE = 2;
  public static final short SVG_LENGTHTYPE_EMS        = 3;
  public static final short SVG_LENGTHTYPE_EXS        = 4;
  public static final short SVG_LENGTHTYPE_PX         = 5;
  public static final short SVG_LENGTHTYPE_CM         = 6;
  public static final short SVG_LENGTHTYPE_MM         = 7;
  public static final short SVG_LENGTHTYPE_IN         = 8;
  public static final short SVG_LENGTHTYPE_PT         = 9;
  public static final short SVG_LENGTHTYPE_PC         = 10;

  public short getUnitType( );
  public float          getValue( );
  public void           setValue( float value )
                       throws DOMException;
  public float          getValueInSpecifiedUnits( );
  public void           setValueInSpecifiedUnits( float valueInSpecifiedUnits )
                       throws DOMException;
  public String      getValueAsString( );
  public void           setValueAsString( String valueAsString )
                       throws DOMException;

  public void newValueSpecifiedUnits ( short unitType, float valueInSpecifiedUnits );
  public void convertToSpecifiedUnits ( short unitType );
}