Central Excise exemption for roofing tiles modifies prior tariff notification to set nil duty, altering excise treatment. Amends the Central Excise tariff notification to exempt roofing tiles by substituting the entry in the tariff Table for the specified serial number with Nil in the duty column, under powers conferred by section 5A(1) of the Central Excise Act, thereby changing the effective rate of duty applicable to roofing tiles.