OGP based on ISO 19111
Used only as part of an ellipsoidal 3D coordinate system in a geographic 3D coordinate reference system, never on its own.
Affine 3D CS. Axes: northing, easting, ellipsoidal height (X,Y,h). Orientations: north, east, up. UoM: m.
Distance of a point from the ellipsoid measured along the perpendicular from the ellipsoid to this point. Positive if upwards or outside of the ellipsoid.