Maybe DotTune is a test for the calibration of the phase detection calibration of the camera. If the requirement for AFMA is that the camera has correct calibration and the lens needs correction, then DotTune should surely work because live view and PD will be correctly aligned. But, if the lens is correctly calibrated and it is the camera that requires calibration, then DotTune will fail. For example, if the camera's PD leaves the factory at effectively -10, then if you test a lens that is perfect using FoCal or the sloping ruler method, an AFMA of +10 is required. But, if you use DotTune, then a reading of -10 for AFMA will be found because the miscalibrated PD will be 10 units less than it should be. Similarly, if the camera is -5 and the lens is +5, FoCal or the ruler will give +10 but DotTune will give +5.