How to attach/remove a comment to a cell (External Data)
You would like to write a comment to describe a number or remove it, here's how
Make sure to be in the Base Alternative/Strategic Alternative/Strategic Building Block → External Data tab.
Once you found the cell you would like to add a comment to, click on it to select it, right-click, and click on Add Comment.
In the window that opens, write your comment, and click somewhere else on the screen.
To remove that comment, either click on the cell again, right-click, and click on Delete Comment, or hover on the black triangle in the corner of the cell with the comment and delete the text in the text-box that appear. Then click somewhere else on the screen.
To indicate it, cells with comments will display a small black triangle in the top right corner of the cell.