Breakpoints allow you to mark a position in a program at which program execution should be interrupted. You can set breaks to occur before or after parenthetical expressions. Breakpoints can only be set from a VLISP text editor window.
Choose
the Toggle Breakpoint toolbar button or press F9 to set the breakpoint.
(For variety, you can set a breakpoint by choosing Debug
Toggle Breakpoint
from the VLISP menu, or by right-clicking the mouse and selecting
Toggle Breakpoint from the resulting shortcut menu.)
If you move the cursor to an ambiguous position, such as in the middle of an expression, VLISP will move the cursor to the nearest parenthesis and display the following message asking whether you agree with the breakpoint placement:

The Toggle Breakpoint works as an on/off switch. When no breakpoint exists, Toggle Breakpoint adds a break; if a breakpoint already exists at the cursor position, Toggle Breakpoint removes it. You can also use the Breakpoint Service dialog to remove breakpoints; see Listing and Viewing the Breakpoints in Your Program for information on this procedure.
Clear All Breakpoints from
the VLISP menu.