Why two points of measurement at sufficiently away from TDC is selected during static TDC determination using dial gauge instead of taking the measurement exactly at TDC position? What is the optimum...

Why two points of measurement at sufficiently away from TDC is selected

during static TDC determination using dial gauge instead of taking the measurement exactly at TDC position? What is the optimum position for dial gauge

measurement for static TDC determination? Justify your answer.