drscheme:debug:get-cm-key in DrScheme Tools Functions
(drscheme:debug:get-cm-key) -> any
Returns a key used with contination-mark-set->list.
The contination mark set attached to an exception record
for the user's program may use this mark. If it does,
each mark on the continuation is the same type as
the input to
drscheme:debug:open-and-highlight-in-file.