Documents that are saved in PaperOffice, then opened and modified from PaperOffice, receive a new document version each time. You can view all versions of the document at any time by clicking the appropriate version icon either in the document list or in document options to see the version history.
You can also easily add documents manually as new versions of existing documents. If you mark a document that has already been saved in PaperOffice, drag and drop a document onto the interface that you want to save as a new version and click on the arrow next to the Save button. Now select "Add as new version for the selected document".
Versioning also occurs when you attach the PaperOffice QR Code to the source document before saving it to PaperOffice, then archiving that document in PaperOffice and next time modifying it outside of PaperOffice. Scan the modified version into PaperOffice afterwards - PaperOffice automatically detects that this document has already been saved and versions it using the QR code.