Previous to version 4.0, there was no distinction between a document file and a document version. In addition, each document version had a 1 to 1 relationship to a document file. That relationship extended to the pages and their layout.
Every time a document file is upload, a corresponding document version object is created. Document versions act like a “view” that presents the pages of document files to the end user in a specific layout.
New in version 4.0.
Since document versions and their pages are nothing more than pointers, they can be modified without affecting their underlying source.
Document version pages can disabled, enabled, appended, removed, or even reordered. All of this is achieved in a non destructive way (the original uploaded file is never changed in any way), all of the changes happen only at the application level for the document version.
There is no limit to the number of versions a document can have. Document versions can also be deleted in any order and at any time.
Although many versions for a single document, only one version can be marked as the active version.
Transformations can be applied to document version pages as they can be applied to document file pages. However, since document file pages are the source for the document version pages, transformations applied to a document file page will be reflected on any document version page, transformations applied a document version page will not be reflected on the source document version file.
Since document versions are virtual objects, they cannot be downloaded. Instead document versions are exported as a PDF and this PDF representation of the document version is then downloaded.