Figure 50 : The uncertainty of the calibration line is at best expressed by the relative repeatability standard deviation. You will not get a value for the relative standard deviation if N = 1 and with N = 2 or N = 3 the standard deviation may be something like a number but nothing useful. This statement is independent of the regulation and certification you may have to follow. Nonsense remains nonsense especially in the quantitative PLC, which is very vulnerable by systematic errors.