Section 1. This Act contains provisions relating to measures for special support and special service for those
1. who are mentally retarded, are autistic or have a condition resembling autism,
2. who have a considerable and permanent, intellectual functional impairment after brain damage when an adult, the impairment being caused by external force or a physical illness, or
3. who have some other lasting physical or mental functional impairments which are manifestly not due to normal aging, if these impairments are major ones and cause considerable difficulties in daily life and, consequently, an extensive need for support and service.