So it is completely filtered by our global illus. It can basically travel across freely, but it is not reabsorbed, nor is it actually secreted. So the global filtration rate, or GFR is equal to the filtration rate of this substance, our inulin. So our doctors basically can study the globeal filtration rate of our kidneys by giving the patient this substance and then study what our renal clearance is of our inulin. Now, let's move on to case number two. In case number two, we also have the substance freely filtered, but now it is fully reabsorbed and it is not secreted.