Unless a contrary intention appears or the context otherwise requires, on and from the commencement of Part 18.4, in any Act (other than this Act), or in any instrument made under any Act or in any other document of any kind—
(a) a reference to a remand centre, youth residential centre or youth justice centre is taken to be a reference to a youth justice custodial centre; and
(b) a reference to a youth justice unit is taken to be a reference to a youth justice community service centre.