Customs valuation rule replaces ad valorem excess threshold with a fixed per tonne rate for goods under Heading 27.09. Amendment to Notification No. 56/85 Customs replaces the prior excess calculation phrasing based on an ad valorem threshold with wording providing calculation on a fixed per tonne rate for goods classified under Heading 27.09, effected under the powers of section 25(1) of the Customs Act, 1962.