 So you don't understand Flat Islands, not a problem. This just applies actions to every face that is both connected and oriented in the same direction as the one you clicked. It's like if Flat Inna and Flat Outer were on at the same time, and it does not care about poly groups. You'll see here, even with a bunch of different poly groups, it only cares about face orientation and if they're connected. Hope that helps. And as always, hope you have a fantastic day, and I'll see you around.