Customs tariff revisions expand blanket duty substitutions across tariff chapters, replacing varied entries with standard ad valorem and specific duties. The Schedule amends the First Schedule to the Customs Tariff Act by systematically substituting entries in column (4) and, where indicated, column (5) across numerous chapters and sub headings, imposing uniform ad valorem or specific duties, while listing specified exceptions that receive alternate rates, 'Nil' or 'Free' treatment, and inserting a Note extending provisions to goods imported through courier service.