The Slots > Trace and Object > Trace submenus provides four options. Slot access on CLOS objects may be traced using these commands.
Break on Read causes a break to the debugger if the slot is accessed for read, either by a defined accessor or by slot-value .
Break on Write causes a break to the debugger if the slot is accessed for write, either by a defined accessor or by slot-value .
Break on Access causes a break to the debugger if the slot is accessed for read or write, either by a defined accessor or by slot-value .