Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xls.php
private function readPane()
    {
        $length = self::getUInt2d($this->data, $this->pos + 2);
        $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);

        // move stream pointer to next record
        $this->pos += 4 + $length;

        if (!$this->readDataOnly) {
            // offset: 0; size: 2; position of vertical split
            $px = self::getUInt2d($recordData, 0);

            // offset: 2; size: 2; position of horizontal split
            $py = self::getUInt2d($recordData, 2);

            // offset: 4; size: 2; top most visible row in the bottom pane
            $rwTop = self::getUInt2d($recordData, 4);

            // offset: 6; size: 2; first visible left column in the right pane
            $colLeft = self::getUInt2d($recordData, 6);

            if ($this->frozen) {
                // frozen panes
                $cell = Coordinate::stringFromColumnIndex($px + 1) . ($py + 1);
                $topLeftCell = Coordinate::stringFromColumnIndex($colLeft + 1) . ($rwTop + 1);
                $this->phpSheet->freezePane($cell, $topLeftCell);
            }
            // unfrozen panes; split windows; not supported by PhpSpreadsheet core
        }
    }
private function readPane()
    {
        $length = self::getUInt2d($this->data, $this->pos + 2);
        $recordData = $this->readRecordData($this->data, $this->pos + 4, $length);

        // move stream pointer to next record
        $this->pos += 4 + $length;

        if (!$this->readDataOnly) {
            // offset: 0; size: 2; position of vertical split
            $px = self::getUInt2d($recordData, 0);

            // offset: 2; size: 2; position of horizontal split
            $py = self::getUInt2d($recordData, 2);

            // offset: 4; size: 2; top most visible row in the bottom pane
            $rwTop = self::getUInt2d($recordData, 4);

            // offset: 6; size: 2; first visible left column in the right pane
            $colLeft = self::getUInt2d($recordData, 6);

            if ($this->frozen) {
                // frozen panes
                $cell = Coordinate::stringFromColumnIndex($px + 1) . ($py + 1);
                $topLeftCell = Coordinate::stringFromColumnIndex($colLeft + 1) . ($rwTop + 1);
                $this->phpSheet->freezePane($cell, $topLeftCell);
            }
            // unfrozen panes; split windows; not supported by PhpSpreadsheet core
        }
    }
Read PANE record.