Certainly, anything for science! Attached is the Dataset 2 screen as it appears on my monitor (100% size). Looking closely, you can see that it is something other than a sigma, but for someone without the best eyes, it can at first glance look like it - especially when the number right next to it is a sigma value.
I am not sure what that symbol is. Perhaps a circle with a line out the left side. But it did not strike me as representing an 'undo' operation. Attached is a different symbol that might communicate the purpose of the button better.
Ed