- Requests a reference to the first older choice point.
- Requests a reference to the frame to which the choice point refers.
- Requests the type. Defined values are
clause(the goal has alternative clauses),
foreign(non-deterministic foreign predicate),
jump(clause internal choice point),
top(first dummy choice point),
catch(catch/3 to allow for undo),
debug(help the debugger), or
none(has been deleted).
- Requests the program counter to which the choice point refers. Only applicable for in-clause choice points.
- Request the clause that will be tried if this choice point is activated.
Only applicable for choice points of type
This predicate is used for the graphical debugger to show the choice point stack.