fusion output about DMP

Hi dear:

we are developing a wearable device installed MPU6050 .

Now I'm studying "motion_driver-5.1.2".

The feature "DMP_FEATURE_6X_LP_QUAT" is a fusion output from gyroscope and accelerometer.

I have no idea about what processing is applied to the fusion output.

High pass? low pass? kalman filter?

I really need your help. thanks.

any advice is appreciated!