"Starting April 2018, all new iOS apps submitted to the App Store must be built with the iOS 11 SDK. All new apps for iPhone, including universal apps, must support the Super Retina display of iPhone X."

I understand that this will apply to new and updated apps. What I do not understand is what constitutes super-retina support. Does this mean all apps must contain 3x images? We have numerous resource assets and the answer to this question would be very helpful. Thanks to anyone who has an answer.