The prefix string will be used directly in XML file that describe the pdf custom metadata inside the PDF file structure. The following characters will render the xml invalid: '&', '<', '>', ' '
Please note that RC4 is considered insecure, but allows to apply encryption on PDF versions 1.4 and 1.5. If possible, prefer generating PDF versions 1.6 or later with AES 128 encryption.
Please note that this format doesn't allow multipage outputs yet, and CDocumentWriter will throw an exception if the case occurs. This possibility will be added in a future release.