code: private function writeWsbool()
      {
          $record = 0x0081; // Record identifier
          $length = 0x0002; // Bytes to follow
          $grbit = 0x0000;
  
          // The only option that is of interest is the flag for fit to page. So we
          // set all the options in one go.
          //
          // Set the option flags
          $grbit |= 0x0001; // Auto page breaks visible
          if ($this->outlineStyle) {
              $grbit |= 0x0020; // Auto outline styles
          }
          if ($this->phpSheet->getShowSummaryBelow()) {
              $grbit |= 0x0040; // Outline summary below
          }
          if ($this->phpSheet->getShowSummaryRight()) {
              $grbit |= 0x0080; // Outline summary right
          }
          if ($this->phpSheet->getPageSetup()->getFitToPage()) {
              $grbit |= 0x0100; // Page setup fit to page
          }
          if ($this->outlineOn) {
              $grbit |= 0x0400; // Outline symbols displayed
          }
  
          $header = pack('vv', $record, $length);
          $data = pack('v', $grbit);
          $this->append($header . $data);
      }
docs: Write the WSBOOL BIFF record, mainly for fit-to-page. Used in conjunction
  with the SETUP record.