@Kimundi Right now Rust hasn’t even come to a decision on whether each family warrants a different target yet. Suffice to say, on a given PC running Windows, you can run an application compiled for any of those families (although phone apps need to be run inside the windows phone emulator, but they’re still technically x86 due to the emulator using hyper-v). For a given application, all libraries and crates need to be compiled for that family, including std and friends, so it is compatible with one target per family approach. However, because nobody from the Rust team has given me any sort of answer on how we’ll be proceeding with this, I can’t give any sort of definitive answer.