Let me add one thing to what Professor Elgie said, and that is about the national accounts system. One reason we're entering into this discussion with Mexico and the U.S. is to try to imagine a regional framework that may in fact be a precursor to what you're talking about. It's a bit easier to manage because there are only three players. In fact, if we can make it work on a North American basis and get transferability, effective taxes, and accounting for emissions, the likelihood is that in the future it's going to transfer to or be very attractive to other countries that are larger and more diverse. It's a great place to start.
