PHPOffice / PhpSpreadsheet

     * @param mixed   $xfIndex The XF format index for the cell

     * @param array $arrcRun Index to Font record and characters beginning

     */

    private function writeRichTextString($row, $col, $str, $xfIndex, $arrcRun)

    {

        $record    = 0x00FD;                   // Record identifier

        $length    = 0x000A;                   // Bytes to follow

        $str = \PhpSpreadsheet\Shared\StringHelper::UTF8toBIFF8UnicodeShort($str, $arrcRun);

        /* check if string is already present */

        if (!isset($this->stringTable[$str])) {

            $this->stringTable[$str] = $this->stringUnique++;

        }

        $this->stringTotal++;

        $header    = pack('vv', $record, $length);

        $data    = pack('vvvV', $row, $col, $xfIndex, $this->stringTable[$str]);

        $this->append($header.$data);

    }

    /**

     * Write a string to the specified row and column (zero indexed).

     * @param mixed   $xfIndex The XF format index for the cell

     * @return integer

     */

    private function writeLabelSst($row, $col, $str, $xfIndex)

    {

        $record    = 0x00FD;                   // Record identifier

        $length    = 0x000A;                   // Bytes to follow

        $str = \PhpSpreadsheet\Shared\StringHelper::UTF8toBIFF8UnicodeLong($str);

        /* check if string is already present */

        if (!isset($this->stringTable[$str])) {

            $this->stringTable[$str] = $this->stringUnique++;

        }

        $this->stringTotal++;

        $header    = pack('vv', $record, $length);

        $data    = pack('vvvV', $row, $col, $xfIndex, $this->stringTable[$str]);

        $this->append($header.$data);

    }

    /**

     * Writes a note associated with the cell given by the row and column.