How to set _ekf_type to EKFType::SITL

I’m not certain what category this belongs to.

In AP_AHRS_NavEKF.cpp it looks like the ekf_type can be EKFType::SITL but I can’t find any place in the code where it is actually set to that value. It is tested for that value and the only place it could possibly be set is in AP_AHRS_NavEKF::active_EKF_type(void) but it only returns that value if it is already that value.

Maybe I’m missing the concept.