The purpose of this part is to provide for—
(a) the delivery to, and sending of postal articles for, patients in authorised mental health services; and
(b) searches of particular patients in authorised mental health services and public sector health service facilities; and
(c) searches of persons on admission to, or entry into, high security units or other authorised mental health services approved by the chief psychiatrist; and
(d) searches of visitors to high security units or other authorised mental health services approved by the chief psychiatrist; and
(e) the power of administrators of authorised mental health services to exclude particular visitors to the service.