AutoCAD 2008 User's
Guide > Create and Modify
Objects > Use Precision
Tools > Use Coordinates and
Coordinate Systems (UCS) >
Enter 3D Coordinates
Cartesian, cylindrical, or spherical coordinates locate points when you are creating objects in 3D.
3D Cartesian coordinates specify a precise location by using three coordinate values: X, Y, and Z.
3D cylindrical coordinates describe a precise location by a distance from the UCS origin in the XY plane, an angle from the X axis in the XY plane, and a Z value.
3D spherical coordinates specify a location by a distance from the origin of the current UCS, an angle from the X axis in the XY plane, and an angle from the XY plane.
