2012

When an operation cannot be undone, the command name is displayed but
no action is performed. Operations external to the current drawing, such as
plotting or writing to a file, cannot be undone.
If you changed modes or used transparent commands during a command,
their effects are undone, along with the effects of the main command.
The U command is equivalent to entering undo 1.
UCS
Quick Reference
See also:
■ Work with the User Coordinate System (UCS)
■ UCSSELECTMODE
Sets the origin and orientation of the current UCS.
Access Methods
Button
NOTE By default, the Coordinates panel is hidden in the Drafting & Annotation
workspace. To display the Coordinates panel, click the View tab, then right-click
and choose Show Panels, and then click Coordinates.
Ribbon: View tab ➤ Coordinates panel ➤ UCS
Menu: Tools ➤ New UCS
Toolbar: UCS
Shortcut menu: Right-click the UCS icon and click an option.
Summary
The UCS is the active coordinate system that establishes the XY plane (work
plane) and Z-axis direction for drawing and modeling. Control the UCS origin
and orientation to make drawing more convenient as you specify points, enter
coordinates, and work with drawing aids, such as Ortho mode and the grid.
1266 | Chapter 21 U Commands