As well as assigning a review mark to an item, you can add a comment to it.
To add a comment to an item
In the Review pane, select one or more items to which you want to add a comment.
To select multiple adjacent items, click the first item, and then hold down the Shift key and click the last item. To select nonadjacent items, click the first item, and then hold down the Ctrl key and click additional items. To select all the items, press Ctrl+A.
In the Comment box at the bottom of the pane, type a new comment.
Click the button at the right of the Comment box.
Discovery Accelerator displays a comment indicator in the Comment present column of the item list to show that you have added the comment.
Click the Comments tab at the bottom of the Reading pane to view the comments assigned to an item. You can also customize the item list columns to add a column that shows the comments on items.
More Information
About the Discovery Accelerator permissions