AutoCAD 2008 User's Guide > Create and Modify Objects > Use Precision Tools > Use Coordinates and Coordinate Systems (UCS) > Specify Workplanes in 3D (UCS) > Understand the User Coordinate System in 3D > 
To enter coordinates relative to the WCS
Concept Procedure Quick Reference
 
 
 

To enter coordinates relative to the WCS

Entering @*2,0,0 specifies a point two units in the X direction of the last point entered relative to the WCS. Entering @2,0,0 specifies a point two units in the X direction of the last point entered relative to the UCS.

In practice, most coordinates are entered relative to the UCS rather than the WCS.