The Revisions List Pane displays document revision information and allows the creation of a new revision.
It lists all the existing document revisions in chronological order with the most recent listed first, and provides a download icon 
on each row so you can download that revision to the desired storage location.
Select 
to open a File Upload window, which allows a new revision to be uploaded. Multiple new revisions are not supported. If the upload succeeds, a row for the revision is added at the top of the revisions list. To upload a new revision, drag and drop a file onto the grid.
Select the 
button to complete the storage of the new revision by adding a date and time stamp to the row. Save between each new revision because only one pending revision can be present. Revisions cannot be individually deleted. Only the whole document with all its revisions can be deleted.
The Revisions List pane is only found on Document object and In Context Edit presentations, and more than one might be present.