Question about the quaternion of the imu_kinematic_measurements.txt && kinematics.cpp

[SunPengHUST]

Hi, I'm trying to reproduce your results on my own to make sure that I really understand your paper Contact-Aided Invariant Extended Kalman Filtering for Robot State Estimation.
When I look the kinematics.cpp, I find the quaternion of the imu_kinematic_measurements.txt is used in
q = Eigen::Quaternion<double>(stod98(measurement[i + 1]), stod98(measurement[i + 2]), stod98(measurement[i + 3]), stod98(measurement[i + 4]));
I do not understand where it means rotation from where to where. This is really strange to me. I would be really appreciated if you can answer this question for me.
Thank you so much in advance for your time!
Best
Sun