Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Shared/OLE/PPS.php
public function _getPpsWk()
    {
        $ret = str_pad($this->Name, 64, "\x00");

        $ret .= pack('v', strlen($this->Name) + 2)  // 66
            . pack('c', $this->Type)              // 67
            . pack('c', 0x00) //UK                // 68
            . pack('V', $this->PrevPps) //Prev    // 72
            . pack('V', $this->NextPps) //Next    // 76
            . pack('V', $this->DirPps)  //Dir     // 80
            . "\x00\x09\x02\x00"                  // 84
            . "\x00\x00\x00\x00"                  // 88
            . "\xc0\x00\x00\x00"                  // 92
            . "\x00\x00\x00\x46"                  // 96 // Seems to be ok only for Root
            . "\x00\x00\x00\x00"                  // 100
            . OLE::localDateToOLE($this->Time1st)          // 108
            . OLE::localDateToOLE($this->Time2nd)          // 116
            . pack('V', isset($this->startBlock) ? $this->startBlock : 0)  // 120
            . pack('V', $this->Size)               // 124
            . pack('V', 0); // 128
        return $ret;
    }
public function _getPpsWk()
    {
        $ret = str_pad($this->Name, 64, "\x00");

        $ret .= pack('v', strlen($this->Name) + 2)  // 66
            . pack('c', $this->Type)              // 67
            . pack('c', 0x00) //UK                // 68
            . pack('V', $this->PrevPps) //Prev    // 72
            . pack('V', $this->NextPps) //Next    // 76
            . pack('V', $this->DirPps)  //Dir     // 80
            . "\x00\x09\x02\x00"                  // 84
            . "\x00\x00\x00\x00"                  // 88
            . "\xc0\x00\x00\x00"                  // 92
            . "\x00\x00\x00\x46"                  // 96 // Seems to be ok only for Root
            . "\x00\x00\x00\x00"                  // 100
            . OLE::localDateToOLE($this->Time1st)          // 108
            . OLE::localDateToOLE($this->Time2nd)          // 116
            . pack('V', isset($this->startBlock) ? $this->startBlock : 0)  // 120
            . pack('V', $this->Size)               // 124
            . pack('V', 0); // 128
        return $ret;
    }
Returns a string with the PPS's WK (What is a WK?).

@return string The binary string