When a document's status is changed from in progress to completed, the approval process begins. At that point, the document's content and metadata can generally no longer be edited — unless the document is returned to in progress.
The publisher, however, has the right to add or correct metadata if needed. The document may have been miscategorised, a review date may have been missed, or something similar. In those cases, it is useful to be able to make corrections without returning the document to in progress.
The publisher cannot, however, edit the content of the document itself, as the approval process is underway.
Only the publisher has these rights.
The video below gives an overview of this functionality.