Customs duty cap limits payable duty on Chapter eleven milling imports to a prescribed ad valorem rate, exempting the excess. Goods under Chapter 11 face a capped customs levy on import: payable duty is limited to an ad valorem rate of 30% ad valorem, and any portion of the duty in the First Schedule exceeding that rate is exempted; the exemption is issued by the Central Government under its statutory power as necessary in the public interest.