Via auxiliary latitudes, Geocart can project the ellipsoid to the sphere and thence to any projection. The choice of auxiliary latitude allows one to preserve conformality, equivalence, or meridian lengths. Some projections (such as this) require explicit ellipsoidal developments in order to yield some other desirable trait, so Geocart has several such specialized ellipsoidal projections. For information about datums let me direct you to here. Feel free to dig deeper either here in the forums or by e-mail. Thank you kindly for your interest.Does Geocart support ellipsoidal projection or does it support only spherical projection?