Button and Axis count on Vive Tracker

[daoshengmu]

I use GetInt32TrackedDeviceProperty() and GetUint64TrackedDeviceProperty() in C++ to get the number of buttons and axes from Vive Tracker. But, I get 4 buttons and 3 axes, just like Vive Controllers have. My Vive Tracker does not dock to any real device, so I suppose it should have 0 button and 0 axis. Is there anything wrong for me to get these information from Vive Tracker?