Extended Assignments module allows creation of task completion objects that could be added to other, referenced objects in order to keep status of who and when marked assignment as completed.
If you want to keep a record (in a structured way), every time someone approves the document, then you need Extended Assignments. Extended assignments will give you a possibility to have next set of information included directly into the document:
Imagine to have a record about assignment completion for every business process in M-Files. By using Extended Assignments you can have information about completed assignments in workflow directly on the M-Files object.
For example, you can generate tasks related to handling new leads. Once your sales complete the assignment you will have this information recorded directly on a lead object.