# Save Changes to PDF Documents

There are two methods that save changes to PDF documents: the `Zend_Pdf::save()` and `Zend_Pdf::render()` methods.

`Zend_Pdf::save($filename, $updateOnly = false)` saves the PDF document to a file. If $updateOnly is `TRUE`, then only the new PDF file segment is appended to a file. Otherwise, the file is overwritten.

`Zend_Pdf::render($newSegmentOnly = false)` returns the PDF document as a string. If $newSegmentOnly is `TRUE`, then only the new PDF file segment is returned.

## Saving PDF Documents

    ...
    // Load the PDF document
    $pdf = Zend_Pdf::load($fileName);
    ...
    // Update the PDF document
    $pdf->save($fileName, true);
    // Save document as a new file
    $pdf->save($newFileName);

    // Return the PDF document as a string
    $pdfString = $pdf->render();

    ...