Retrospective amendment validates actions under the amended rule as if the amendment had always been in force. Amendment to rule 16 retroactively deems the rule amended for the scheduled period and validates any actions taken during that period by treating them as if the amendment had been in force; it also deems the Central Government to have had retrospective rulemaking power for that period and declares that no act or omission shall be punishable to the extent it would not have been punishable but for this section.