Otherwise the system default exception handler is called. Dynamic predicate, normally not defined. Called by the Prolog system on run-time exceptions. Future versions might handle signal handling, floating exceptions and other runtime errors via this mechanism. The values for Exception are described below.
Name refers to the name and Arity to the arity of the undefined predicate.
If the predicate fails Prolog will print the default error warning and start the tracer. If the predicate succeeds it should instantiate the last argument either to the atom fail to tell Prolog to fail the predicate or the atom retry to tell Prolog to retry the predicate. This only makes sense if the exception handler has defined the predicate. Otherwise it will lead to a loop. The Action argument is ignored.