Documentation on extended kalman filter

[user-001]

The example ekfimu_13states specifies accelerometer reference value as {0,0,1} and magnetometer reference value as {1,0,0}, but doesn't say which coordinate system it uses, either the left-handed coordinate system (x-North, y-East, Z-up) or the right-handed coordinate system (x-North, y-West, Z-up).

Also, I am uncertain about the convention regarding roll, pitch and yaw angles. Does clockwise rotation about an axis, looking from it, contribute to positive angle change or vice versa?