Retrospective amendment of customs notification validates prior acts and confirms the government's retrospective amendment power. The enactment retrospectively amends the customs notification G.S.R. 785(E) as specified in the Third Schedule from the dates in column (4), and declares that any action taken under the notification shall be deemed always to have been valid and effective as if the amended notification had been in force. It also deems the Central Government to have had and exercised retrospective power to amend that notification at all material times.