Retrospective excise exemption for specified goods manufactured for central government use, and retrospective amendment power affirmed. The amendment inserts a retrospective exemption entry for all goods within the specified classification where the goods are manufactured by a Central Government factory and are intended for use by any Department of the Central Government, effective from 20 April 2011, and declares that the Central Government shall be deemed to have had the authority to amend the notification retrospectively as if it possessed the statutory amendment power at all material times.