Hello, I would like to ask a question about the ROC curve that plots sensitivity against 1-specificity for all possible threshold settings of a diagnostic test. Each point on the ROC curve represents a different cutoff value. For a perfect diagnostic test the ROC curve would be vertical from (0,0) to (0,1) and then horizontal to (1,1). In this case of a perfect test I would like to know where are the other cutoff values represented in this line, as the perfect discrimination is assumed to be for only 1 cutoff value, which is the one generating the previous coordinates. Or in the case of a perfect test only the cutoff value giving the perfect discrimination is represented in the curve?