1. Harmonic factor of nth harmonic (HF)
2. Total Harmonic distortion (THD)
3. Distortion Factor (DF): Indicates the amount of HD that remains in a particular waveform after the harmonics have been subjected to second-order attenuation.
4. Lowest order harmonic (LOH): The harmonic component whose frequency is closest to the fundamental and its amplitude is greater than or equal to 3% of the amplitude of the fundamental component.