Save this configuration set into an xml.dom.Element object.

def save_xml(self, doc, element):
        '''Save this configuration set into an xml.dom.Element object.'''
        element.setAttributeNS(RTS_NS, RTS_NS_S + 'id', self.id)
        for c in self._config_data:
            new_element = doc.createElementNS(RTS_NS,
                                              RTS_NS_S + 'ConfigurationData')
            c.save_xml(doc, new_element)
            element.appendChild(new_element)