public function get_embeddable_markers() {
        if (empty($this->embeddablemarkers)) {
            $markers = '';
            foreach ($this->get_players() as $player) {
                foreach ($player->get_embeddable_markers() as $marker) {
                    if ($markers !== '') {
                        $markers .= '|';
                    }
                    $markers .= preg_quote($marker);
                }
            }
            $this->embeddablemarkers = $markers;
        }
        return $this->embeddablemarkers;
    }