HTER consistency in metrics

Several metrics and plots report HTER but I am not sure it is calculated the same way in all cases.

For examples, bob measure metrics and bob measure epc both report HTER. However, I don't think they are calculated the same way.

What should be HTER anyway @bob? at least in biometrics, we have FMR, FNMR, FAR, and FRR. Is HTER = (FMR+FNMR)/2 or HTER = (FAR+FRR)/2?

Assuming:

FAR = FMR * (1 - FTA)
FRR = FTA + FNMR * (1 - FTA)