When adding a text watermark you may notice that instead of the text you entered for the watermark, question marks (???) appear when opening the document in the Viewer.
This is because text watermarks are restricted to UTF-8 characters only. You can find a UTF-8 character chart at http://www.utf8-chartable.de/
If you want to use characters outside the UTF-8 range (for example Japanese text), create the watermark as an image and use the Image Watermark feature instead.
NOTE FOR PUBLISHERS
While text watermarks are restricted to UTF-8 characters, the contents of the document are not. So, documents in different languages (Japanese, Russian, Hindi etc.) will be displayed correctly.