You can set and query stops using the foreign conjunctions dbss (13!:3) and dbsq (13!:2), and using the utilities dbstop and dbstopme.
You can also set and view stops with Debug:
The stop line, stop all lines and stop name buttons in the Debug toolbar let you change stops in the currently displayed definition, or visible name.
The Debug Stop Manager lets you set stops on any active definition.
For names whose definition has more than one line, Debug distinguishes between stops set on specific lines (marked with *) and stops set on all lines (marked with |). For one-line definitions, only the "all lines" marker is used.
Set stops on all lines to single-step through definitions.
The namelist in the Stop Manager defaults to the selected definition (if any), and the names on the stack. Select the In Locale checkbox to view names by locale. Place the cursor on a name, and run the Stop Manager toolbar button to view that name.
Comment lines are ignored when setting stops.
Since you may set stops outside of Debug, it may be that the actual stop settings differ from those stored by Debug when it handled the last event. However, on any subsequent event handled by Debug, the stored stop settings are updated. Therefore you are free to change stop settings manually when using Debug.