private function readSharedFmla()
    {
        $length = self::getUInt2d($this->data, $this->pos + 2);
        $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);

        // move stream pointer to next record
        $this->pos += 4 + $length;

        // offset: 0, size: 6; cell range address of the area used by the shared formula, not used for anything
        $cellRange = substr($recordData, 0, 6);
        $cellRange = $this->readBIFF5CellRangeAddressFixed($cellRange); // note: even BIFF8 uses BIFF5 syntax

        // offset: 6, size: 1; not used

        // offset: 7, size: 1; number of existing FORMULA records for this shared formula
        $no = ord($recordData[7]);

        // offset: 8, size: var; Binary token array of the shared formula
        $formula = substr($recordData, 8);

        // at this point we only store the shared formula for later use
        $this->sharedFormulas[$this->baseCell] = $formula;
    }