2012

Object
Aligns the UCS to a selected 2D or 3D object. The UCS can be aligned with
any object type except xlines and 3D polylines.
Move the cursor over an object to see a preview of how the UCS will align,
and click to place the UCS. In most cases, the UCS origin will be located at
the endpoint that is nearest to the specified point, the X axis will align to an
edge or tangent to a curve, and the Z axis will align perpendicular to the object.
Previous
Restores the previous UCS.
You can steps back through the last 10 UCS settings in the current session.
UCS settings are stored independently for model space and paper space.
View
Aligns the XY plane of the UCS to a plane perpendicular to your viewing
direction. The origin point remains unchanged, but the X and Y axes become
horizontal and vertical.
World
Aligns the UCS with the world coordinate system (WCS).
TIP You can also click the UCS icon and choose World from the origin grip menu.
X, Y, Z
Rotates the current UCS about a specified axis.
UCS | 1269