2011

Previous
Restores the previous UCS.
The last 10 user coordinate systems created in model space and the last 10
created in paper space layouts are retained. Repeating this option steps back
through one set or the other, depending on which space is current.
If you have saved different UCS settings in individual viewports and you switch
between viewports, the different UCSs are not retained in the Previous list.
However, if you change a UCS setting within a viewport, the last UCS setting
is retained in the Previous list. For example, changing the UCS from World
to UCS1 would retain World at the top of the Previous list. If you then switch
viewports with Front as the current UCS, and then change the UCS to Right,
the Front UCS is retained at the top of the Previous list. If you then choose
the UCS Previous option twice in this viewport, the UCS setting changes to
Front, and then back to World. (UCSVP system variable)
View
Aligns the XY plane of the user coordinate system to a plane perpendicular to
your viewing direction. The origin point remains unchanged, but the X and
Y axes become horizontal and vertical.
World
Sets the current user coordinate system to the world coordinate system (WCS).
The WCS is the basis for all user coordinate systems and cannot be redefined.
X, Y, Z
Rotates the current UCS about a specified axis.
Point your right thumb in the positive direction of the X axis and curl your
fingers. Your fingers indicate the positive rotation direction about the axis.
1978 | Chapter 21 U Commands