Developing these tests is an iterative process. You start out perhaps focusing on your standardization, and you have a proposed clinical use, and you measure in that context. And then, if the assay performs well, and then you find out well, it doesn't quite perform so well for the given use, you go back and you adjust your assay. But you always have to retest. You have to go through these loops a number of times until you finally go to a prospective trial.