Excise duty cap limits payable excise on specified machinery and goods to a fixed effective ad valorem rate. Limits excise liability by exempting, under section 5A, so much of the duty on goods specified by listed Chapter 84 and 85 headings as exceeds the amount calculated at the rate of 10% ad valorem, thereby capping the effective excise charge on those tariff entries and identifying certain item level exclusions within the Table.