Alt + click layering
I am working non-destructively and can't for the life of me remember what holding the alt key (on a PC) and clicking between two layers does. I notice that the square with the arrow pointing down shows up with the arrow pointing down on the top layer but I can't remember what function that option provides in layering non-destructively. I swear this function was to apply various effects non-destructively to the layer below it but now I can't remember how to control that. Thank you and sorry for the rambling question.
