 These three municipalities were separated from their respective provinces to form the Metropolitan Manila Area on 7 November 1975 by virtue of Presidential Decree No.824; Metro Manila was represented in the Interim Batasang Pambansa as Region IV from 1978 to 1984.Among the amendments to the 1973 Constitution of the Philippines which were approved in the January 1984 plebiscite was a new apportionment ordinance for the election of Regular Batasang Pambansa members, as embodied in Batas Pambansa Blg.