Duty exemption for rotor blade inputs requires pre-clearance certification from a senior government officer before tax-free supply. The amendment adds S.No. 237A granting a nil duty exemption for goods specified in newly inserted List 9A when used for manufacture of rotor blades for wind operated electricity generators, and introduces Condition 58A requiring, prior to clearance, a certificate from a senior government officer recommending the exemption and certifying that the goods are required for rotor blade manufacture.