Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Writer/Xls/BIFFwriter.php
protected function storeBof($type)
    {
        $record = 0x0809; // Record identifier    (BIFF5-BIFF8)
        $length = 0x0010;

        // by inspection of real files, MS Office Excel 2007 writes the following
        $unknown = pack('VV', 0x000100D1, 0x00000406);

        $build = 0x0DBB; //    Excel 97
        $year = 0x07CC; //    Excel 97

        $version = 0x0600; //    BIFF8

        $header = pack('vv', $record, $length);
        $data = pack('vvvv', $version, $type, $build, $year);
        $this->append($header . $data . $unknown);
    }
protected function storeBof($type)
    {
        $record = 0x0809; // Record identifier    (BIFF5-BIFF8)
        $length = 0x0010;

        // by inspection of real files, MS Office Excel 2007 writes the following
        $unknown = pack('VV', 0x000100D1, 0x00000406);

        $build = 0x0DBB; //    Excel 97
        $year = 0x07CC; //    Excel 97

        $version = 0x0600; //    BIFF8

        $header = pack('vv', $record, $length);
        $data = pack('vvvv', $version, $type, $build, $year);
        $this->append($header . $data . $unknown);
    }
protected function storeBof ( $ type ) { $ record = 0x0809 ; // Record identifier    (BIFF5-BIFF8) $ length = 0x0010 ; // by inspection of real files, MS Office Excel 2007 writes the following $ unknown = pack ( 'VV' , 0x000100D1 , 0x00000406 ) ; $ build = 0x0DBB ; //    Excel 97 $ year = 0x07CC ; //    Excel 97 $ version = 0x0600 ; //    BIFF8 $ header = pack ( 'vv' , $ record , $ length ) ; $ data = pack ( 'vvvv' , $ version , $ type , $ build , $ year ) ; $ this -> append ( $ header . $ data . $ unknown ) ; }
Writes Excel BOF record to indicate the beginning of a stream or
sub-stream in the BIFF file.

@param int $type type of BIFF file to write: 0x0005 Workbook,
0x0010 Worksheet
Writes Excel BOF record to indicate the beginning of a stream or sub - stream in the BIFF file .