-Orbit corrections are provided in along-track, cross-track and radial components. The along-track component is parallel to the velocity vector, the cross-track component is perpendicular to the plane of motion and the radial component is perpendicular to both along-track and cross-track components. The three components form an orthogonal system in WGS-84. +Orbit corrections are provided in along-track, cross-track and radial components. These components are defined in the Earth-fixed, Earth-centered reference frame of the broadcast ephemerides. For an observer in this frame, the along-track component is parallel to the velocity vector, the cross-track component is perpendicular to the plane of motion and the radial component is perpendicular to both along-track and cross-track components. The three components form a right-handed orthogonal system.