I don't understand how to point the IMU to the X, - X, Y, - Y, Z, - Z axes during the data collection process?

[Hugo-Xu-maker]

The code modification was written very well. But there are some operational aspects that I don't quite understand. The IMU device has already indicated the X and Y axes, and the positive direction of the Z axis. The operations in the code that point to the coordinate axis respectively refer to collecting data by pointing the IMU's X axis to the positive and negative directions of the X, Y, and Z axes? Or what kind of operation? I sincerely look forward to your reply.