"Screen Space Fade" function?

I’m not sure exactly what this means. I’m sure I look dumb for asking this question, but anything to help my projects.

Under prop_static (and probably more entities) there is a function called “Screen Space Fade”

It says

I think I know what is saying, but I’m not exactly sure, as I want to be precise when using this, if I use it. If anyone can tell me what “Yes” does on this function, then the help would be most appreciated. Thanks~

Edit: Yes, I’ve googled for about 10 minutes. Valve wiki doesn’t have anything, I believe.

If I remember correctly, it makes models fade away when you’re too far from them.

So if you used a value of 50, the object would fade when you were far enough away that it only occupied 50 pixels on your screen.