16 Papal cloister should be maintained in the case of nuns engaged exclusively in the contemplative life. However, it must be adjusted to conditions of time and place and obsolete practices suppressed. This should be done after due consultation with the monasteries in question. But other nuns applied by rule to apostolic work outside the convent should be exempted from papal cloister in order to enable them better to fulfill the apostolic duties entrusted to them. Nevertheless, cloister is to be maintained according to the prescriptions of their constitutions.
Source: Perfectae Caritatis (Vatican.va)