X, Y, and Z axes

An expression for coordinates, with separate meanings for Earth Centered (EC) Cartesian and rectangular coordinates.

In the EC Cartesian system, X refers to the direction of the coordinate axis running from the system origin to the Greenwich Meridian; Y to the axis running from the origin through the 90-degree east longitude meridian, and Z to the polar ice cap.

In rectangular coordinate systems, X refers to the east-west axis, Y to the north-south axis, and Z to the height axis.