code: private Boolean processYESNO(
            StylesheetHandler handler, String uri, String name, String rawName, String value)
              throws org.xml.sax.SAXException
    {
  
      // Is this already checked somewhere else?  -sb
      if (!(value.equals("yes") || value.equals("no")))
      {
        handleError(handler, XSLTErrorResources.INVALID_BOOLEAN, new Object[] {name,value}, null);
        return null;
     }
   
       return new Boolean(value.equals("yes") ? true : false);
    }
docs: Process an attribute string of type T_YESNO into
  a Boolean value.
  
  @param handler non-null reference to current StylesheetHandler that is constructing the Templates.
  @param uri The Namespace URI, or an empty string.
  @param name The local name (without prefix), or empty string if not namespace processing.
  @param rawName The qualified name (with prefix).
  @param value A string that should be "yes" or "no".
  
  @return Boolean object representation of the value.
  
  @throws org.xml.sax.SAXException