AutoCAD 2008 User's Guide > Create and Modify Objects > Use Precision Tools > Use Coordinates and Coordinate Systems (UCS) > Specify Workplanes in 3D (UCS) > Control the User Coordinate System in 3D > 
Control the User Coordinate System in 3D
Concept Procedure Quick Reference
 
 
 

To define a new UCS origin in 3D

Z axis

To define a new UCS with particular X and Y axes

To shift the XY plane

To select a UCS preset

To restore the location and orientation of the previous UCS