protected function create_regObject($group, $key, $originatingSource)
    {
        $regObj_node = $this->addChild($this->working_node, 'registryObject');
        $regObj_node->setAttribute('group', $group);
        $this->addChild($regObj_node, 'key', $key);
        $this->addChild($regObj_node, 'originatingSource', $originatingSource);
        $this->working_node = $regObj_node;
    }