I think the biggest thing is that markets annually ebb and flow. Even during the year they'll right themselves; they'll change. It's a matter of sitting down and planning throughout that year what is sold, what you expect to move, and putting a plan in play.
If it's in legislation, it's hard and fast and has to measure up to that level. With regulations they can be adjusted in order to facilitate more potash that year. If there is a failure in grain, then you can adjust and move more potash should that be required.
It gives you that ebb and flow on a scale that's much easier to administer than something locked in legislation. That's generally the reason for it.