Ellipsoids

Using ellipsoids rather than datums is valid as long as the horizontal datums involved in reprojecting between different map projections are not different.

Note: If different horizontal datums use the same ellipsoid, datum codes must be used. If ellipsoid codes are used, the software incorrectly treats the ellipsoid as the same datum.

The following defaults are provided when there is a reprojection that involves datum shifts.

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