Edge-aware seamless editing criteria

Camera Raw 11.4 makes seamless edge-aware 360-degree panoramas. It doesn't do so on all images, so how does it know that an equirectangular image is a spherical panorama?

1. Is there certain meta data required, and if so, what?
2. If metadata is required, then it would imply that some image types can not be edited in this way, such as PNGs?
3. If I don't have the required metadata, how can I add it, or is there a checkbox to enable seamless edge-aware editing?