bore that might bring oil or hydro carbons into what we call the geological formation potentially to the sub sea floor. some questions were raised yesterday about the implications of leakage and how that interfaced with the test as we start to shut down the valves and increase pressure in the capping stack. i'll go over that process in a minute. what we might expect, even low probability, high consequence outcomes. as a result of that, we asked bp to go back and give us some more information on the structural strength of certain portions of the casing pipes. they had run down there particularly around the 22-inch and 18-inch casing pipes. we asked for some more information about assumptions that could lead to irreversible leakage outside the well from external experts. and we thought about what kind of thresholds we would need to look at as we ran the well integrity test. that took us about 24 hours to work through all of that.