In a Certified PDF workflow, a PDF document can go through various editing sessions, done by various users. A Certified PDF document can “remember” all the changes that were made during a given session and can store the information about these changes per session (“incrementally”) as you save your PDF document.
This way of managing and saving changes has a big advantage: You know exactly which changes have been made in which session and by whom. Moreover, these changes can be presented to you in the form of a “snapshot”: a view of the status of the PDF document at the time it was saved at the end of a session.
And you can do even more: You cannot only view the state of the PDF document in a given previous editing session, you can also save this snapshot as a separate PDF document. This is called the roll-back mechanism. When editing PDF documents, you may have experienced “one-change-too-far” situations, in which you made a change, got an undesired result but also saved the PDF document. No problem in a Certified PDF workflow: you can revert to any previously saved state of a PDF document, provided that you save your Certified PDF document using the "incremental save" method (see Save options).
A snapshot is a complete backup of the PDF document at the time it was saved after an editing session. You save a snapshot to revert to a previous version of your PDF document. However, you do not necessarily have to save this snapshot at the end of each session. You can simply select any session from a list and save its snapshot at any stage in your workflow.
Consider the following example. You have created a Certified PDF document in which you use only black text and one spot color. The document has been designed to be printed on an offset press. At some point in the workflow, however, you also want to print this PDF document on a digital four-color press and therefore, you change the spot color into its CMYK counterpart throughout your entire PDF document. You may use Enfocus PitStop Pro, for example, to do this. This means that the latest version of your PDF document contains only CMYK colors. But, you also need to reprint this PDF document on an offset press using the spot color. You can then simply select a version which still has the spot colors, save its snapshot as a separate PDF document and send this PDF file to your offset printer.
You can view snapshots of a Certified PDF document in the following ways: