Today, Apple emailed iOS developers to explore new features in iOS 11 like ARKit. In that email, the company also announced that all new apps submitted from April 2018 onward must be built with the iOS 11 SDK and must support the iPhone X’s new display.

This was Apple’s complete message to developers on the subject:

iOS 11 has brought innovative features and the redesigned App Store to hundreds of millions of customers around the world. Your apps can deliver more intelligent, unified, and immersive experiences with Core ML, ARKit, new camera APIs, new SiriKit domains, Apple Music integration, drag and drop for iPad, and more.

Starting April 2018, all new iOS apps submitted to the App Store must be built with the iOS 11 SDK, included in Xcode 9 or later. All new apps for iPhone, including universal apps, must support the Super Retina display of the iPhone X.

The email didn’t clarify exactly what support for the iPhone X’s “Super Retina” screen means—does it just mean the resolution and aspect ratio must be supported, or do developers also have to update their apps to respect the rounded corners, sensor array (which many people call “the notch”), and the home indicator?