function _storeMergedCells()
    {
        // if there are no merged cell ranges set, return
        if (count($this->_merged_ranges) == 0) {
            return;
        }
        $record   = 0x00E5;
        $length   = 2 + count($this->_merged_ranges) * 8;

        $header   = pack('vv', $record, $length);
        $data     = pack('v',  count($this->_merged_ranges));
        foreach ($this->_merged_ranges as $range) {
            $data .= pack('vvvv', $range[0], $range[2], $range[1], $range[3]);
        }
        $this->_append($header . $data);
    }