You can set a breakpoint in any form which might be evaluated, except for
The breakpoint can be at the start, function call or return point of the form.
For each of the load source, load fasl, compile defun and compile buffer operations, breakpoints are activated only after the operation has finished.
A locatable defining form is a named defining form that can be located by the Dspec system (for example by the
editor command). This includes
and all the standard Common Lisp definers. For more information about the Dspec system, see the
LispWorks User Guide and Reference Manual
When not at the current stepping position, a breakpoint is highlighted red in the Stepper source area. When the same source code is also visible in an Editor tool, the breakpoint is visible there too.
LispWorks IDE User Guide (Windows version) - 25 Nov 2011