Passing Pick Points to AutoCAD Commands
Command Submission
System and Environment Variables
An UNDO group is explicitly created around each command used with the command function. If a user enters U (or UNDO) after running an AutoLISP routine, only the last command will be undone. Additional entries of UNDO will step backward through the commands used in that routine. If you want a group of commands to be considered a group (or the entire routine), use the UNDO Begin and UNDO End options.