Exemption period computation now measured from commencement of commercial production of expanded capacity, with retrospective amendment and non punishment safeguard. The amendment directs that the exemption period for units undertaking substantial expansion is to be computed from the commencement of commercial production of the expanded capacity; it deems the notification amended retrospectively, affirms the Central Government's retrospective amendment power, includes a non punishment declaration for acts that would not have been offences absent the retrospective amendment, and takes effect from the Bill's presidential assent.