Stop Once from the VLISP menu. When this item is selected, the evaluation of the first LISP expression will be interrupted. After that you can resume program execution using various Debugger commands. Another way to enter into the debugger mode is to set a breakpoint, as shown in .The easiest way to start debugging is to choose Debug
When a break occurs, the corresponding VLISP text editor window will show the current LISP expression at the point which the break took place. A break loop marker will appear in the Console window. Using the Console window, you can access and manipulate the program environment in which the break occurred. You can also examine variables using the Watch window.