Discussion: “Theoretical Basis for Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles” (Murdock, J. W., and Keyser, D. R., 1991, ASME J. Eng. Gas Turbines Power, 113, pp. 228–232) and “A Method for the Extrapolation of Calibration Data of PTC 6 Throat Tap Nozzles” (Murdock, J. W., and Keyser, D. R., 1991, ASME J. Eng. Gas Turbines Power, 113, pp. 233–239)