It is on page 141 of the User Manual - photo of page shown hereThread closed but I just want to add that this icon is nowhere to be found in the manual. Even a google search was fruitless, I forgot even where I found my answer. I feel you OP.
So you're saying the internet is just like being married....?Love the internet... you can guarantee that even when you're 100% sure of something, you still can be wrong!