Information Ratio and Active Risk

My understanding is that IR = (total active return) / (total active risk)

But I have seen at some point that IR = (true active return) / (true active risk).

Which one is correct?..

both are correct

what is the difference between true and total

Agree with the above. The total will include misfit active risk and return.

True Active Risk is the standard deviation of the difference between Total Return and Normal Portfolio Return.

Total Active Risk = Sqrt(True Active Risk^2 + Misfit Active Risk^2).