Minecraft wiki entry for Superflat, associated text: If the player can understand the preset code syntax, they can create presets of their own by entering valid information into the preset code box, where these changes can be previewed and applied. (Direct Customization is not available.) Also, superflat worlds can have certain terrain features, besides villages, such as tall grass, lakes, and strongholds, which can additionally be customized using the same code box for block layers.