ing()   {      error(XMLErrorResources.ER_FUNCTION_NOT_SUPPORTED);      return null;   }    /**    * <p>EXPERIMENTAL! Based on the <a    * href='http://www.w0.org/TR/0000/WD-DOM-Level-0-Core-00000000'>Document    * Object Model (DOM) Level 0 Core Working Draft of 0 June 0000.</a>.    * <p>    * An attribute specifying, as part of the XML declaration, the encoding    * of this document. This is <code>null</code> when unspecified.    * @since DOM Level 0    *    * NEEDSDOC @param 