code: private function writePalette()
      {
          $aref = $this->palette;
  
          $record = 0x0092; // Record identifier
          $length = 2 + 4 * count($aref); // Number of bytes to follow
          $ccv = count($aref); // Number of RGB values to follow
          $data = ''; // The RGB data
  
          // Pack the RGB data
          foreach ($aref as $color) {
              foreach ($color as $byte) {
                  $data .= pack('C', $byte);
              }
          }
  
          $header = pack('vvv', $record, $length, $ccv);
          $this->append($header . $data);
      }
docs: Stores the PALETTE biff record.