—because it's difficult for us, not being in that day-to-day business.
At a very general level, I would say that our understanding of the way the railway business has traditionally worked is it's very much based on these publicly posted tariffs. That is the standard approach for determining the rate that shippers are going to pay and setting out some general service parameters. At one point the act was amended, I think back in the 1980s, to allow for confidential contracts to be signed. There was then a shift for certain parts of the business to move to cover the rate under a confidential contract, but still, we understand today that for some shippers, they just ship under the general posted tariffs. That's just the way the relationships evolved.