Undo a Single Action

The simplest method of backtracking is to use the UNDO or U commands to undo a single
action. Many commands include their own U (undo) option so that you can correct mistakes
without leaving the command. When you are creating lines and polylines, for example,
enter u to undo the last segment.

Undo Several Actions at Once

Use the Mark option of UNDO to mark an action as you work. You can then use the Back
option of UNDO to undo all actions that occurred after the marked action. Use the
Begin and End options of UNDO to define a set of actions to be treated as a group.

You can also undo several actions at once with the Undo list on the Standard toolbar.

Reverse the Effect of Undo

You can reverse the effect of a single U or UNDO command by using REDO immediately
after using U or UNDO.

You can also redo several actions at once with the Redo list on the Standard toolbar.

Erase Objects

You can erase any object that you draw. If you accidentally erase the wrong object,
you can use the UNDO command or the OOPS command to restore it.

Cancel a Command

You can cancel a command without completing it by pressing Esc.