There are two tabs in the panel: Dependencies and Revisions.

The Dependencies panel shows all of the current dependencies for the on-screen assembly or drawing.

The View button  allows the user to view the document in the web viewer. 

The Revision panel shows all of the revisions for the document on the screen.

A new revision can be added by Add Revision button. 

The View Revision Items button   will show the contents of the revision:

 

Edit Revision Buttonis used to edit the revision comment:

Download button  will download a zipped file that includes all the files in the revision.