Tariff revision for non ferrous metals updates classification and duty structure, altering ad valorem and specific duty treatments. Substituted Fourth Schedule entries reset classification and rates of duty for copper, zinc, aluminium and lead, each defining the metal to include predominating alloys and itemising unwrought, waste and scrap, wrought forms, castings, wires, plates/sheets/strips/blanks/foils, powders/flakes, pipes/tubes and shells/blanks or hollow sections with specified ad valorem and/or specific rupee per metric tonne duties and detailed explanatory definitions governing terms and dimensional thresholds for classification.