U command

The U command is used to quit the latest operation.

Command Access:

Menu : Edit > Undo
Command : U
Shortcut : CTRL+Z

Function Description:

Users could input a U to get back one step. They could also input many times to get to the beginning of current drawing.
If some operations could not be given up, it will display the command name without any change. It could not quit external operations of current drawing, such as printing or written to a file.
During the operation of U, only the main command is valid and all transparency commands are invalid.
The U command is equivalent to input "undo 1".