public function serializeContentObjectAttribute( $package, $objectAttribute )
    {
        $node = $this->createContentObjectAttributeDOMNode( $objectAttribute );

        /** @var $eZTags eZTags */
        $eZTags = $objectAttribute->content();
        if ( !$eZTags instanceof eZTags )
            return $node;

        $dom = $node->ownerDocument;

        $idStringNode = $dom->createElement( 'id-string' );
        $idStringNode->appendChild( $dom->createTextNode( $eZTags->attribute( 'id_string' ) ) );
        $node->appendChild( $idStringNode );

        $keywordStringNode = $dom->createElement( 'keyword-string' );
        $keywordStringNode->appendChild( $dom->createTextNode( $eZTags->attribute( 'keyword_string' ) ) );
        $node->appendChild( $keywordStringNode );

        $parentStringNode = $dom->createElement( 'parent-string' );
        $parentStringNode->appendChild( $dom->createTextNode( $eZTags->attribute( 'parent_string' ) ) );
        $node->appendChild( $parentStringNode );

        $localeStringNode = $dom->createElement( 'locale-string' );
        $localeStringNode->appendChild( $dom->createTextNode( $eZTags->attribute( 'locale_string' ) ) );
        $node->appendChild( $localeStringNode );

        return $node;
    }