Thank you. I actually do think I understand what this is. So I do really appreciate that.

I guess my next question, then, and again it could be something for the briefing or in the detailed dive with the departments but is -- how much validity or certainty is there around this number?

So, for example, using your own example of asbestos, oftentimes when the government is dealing with the decommissioning of a building, they don't know what they have until there's a time that they come into that building and start assessing it. And as any consultant in the environmental world will tell you, and that's why we love to caveat our reports, is that there are unknown conditions and therefore they -- those types of projects can really spiral.

So I guess I'm just curious to know -- and I don't need to know today, but what is the certainty of this number, really, when we look at the uncertainty in assessing environmental issues and liabilities. Thank you.