Estimated heading error in degrees (±), or -1 when unknown, e.g. while
the compass needs calibration. On Android this is an approximation
derived from the sensor accuracy status.
Full device attitude as a row-major 3x3 rotation matrix mapping a
world vector (East, North, Up — true north) to screen coordinates
(x to the right of the screen, y to its top, z out of the screen
towards the viewer), for the current UI orientation.