So I have always been confused about this, not the concept, just where to get CDMVT from. Compass Deviation Magnetic Variation True then use GET- Gyro East Error (Add) True . For example what compass do you use for Compass in CDMVT? Magnetic is obviously the standard compass and true is gotten from the difference between magnetic and variation adding east and subtracting west. Deviation is the error between the Compass and magnetic and variation is from the chart correct? I know these are basics, I just never asked the questions when I should have when initially learning it. Thank you.