I have an iPhone app with interface languages in Toki Pona and Dothraki, which do not have ISO 639-3 codes. According to the ISO 639-3 standard, you can use the range qaa-qtz to represent languages for local use, which I have done (Toki Pona = qtp, Dothraki = qdt), but still get the warning from XCode "Unrecognized Locale".I have an iPhone app with interface languages i