private function _renderproperties() {
        $out = '';

        $out   .= '<divisions>'.$this->divisions.'</divisions>';
        $staves = 1;

        if (isset($this->key)) {
            $out .= $this->key->toMusicXML();
        }

        if (isset($this->time)) {
            $time = $this->time;
            if (!$time instanceof Time) {
                $time = new Time($time);
            }

            $out .= $this->time->toMusicXML();
        }

        // we count the number of clefs, and that is our number of staves
        $clefs = '';
        if (isset($this->clef)) {
            if (!is_array($this->clef)) {
                $this->clef = array($this->clef);
            }

            $num = 0;
            foreach ($this->clef as $clef) {
                $num++;
                $clefs .= $clef->toMusicXML($num);
            }

            $staves = $num;
        }

        if (isset($this->staves)) {
            $staves = $this->staves;
        }

        // output staves first, and then clefs.
        $out .= '<staves>'.$staves.'</staves>';
        $out .= $clefs;

        return $out;

    }