A symbol representing the name of the system. The system must have been defined using the
or not present then
works silently. Otherwise a plan of the actions which
intends to carry out is printed. What happens next depends on the value of
displays each action in the plan one at a time, and asks you if you want to carry out this particular action. The answer executes the rest of the plan without further prompting,
without further processing, and
work as expected.