This is definitely a ‘just because you can doesn’t mean you should’ moment (-: [quote='848220021, zosoz, /thread/848220, /profile/zosoz'] What are the XNU devs planning on doing with them? [/quote] To be clear, we can’t talk about The Future™ here on the forums. See tip 3 in Quinn’s Top Ten DevForums Tips. However, you can see this feature already being used by the Objective-C runtime. Which brings me back to my original point. While this is technically API, you’d want to think very carefully before using it in a product that you ship to a wide range of end users. The Objective-C runtime has the advantage that it’s built in to the system, so if the system changes in a way that breaks this API it can adapt. In contrast, any third-party products in the same situation would require an urgent, and potentially very difficult, update. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = eskimo + 1 + @ + apple.com