Local Soundness up to a few conditions and caveats.
First, only for tau steps. Secondly, this currently doesn't take care of argument steps very well. Essentially, the problem is that a single location can start working on an argument (because to it, it looks like the function is done), while the function is not finished computing at the choreography level. I think to fix this, we'll need to change the compiler and possibly the target language again.