关税约束，简单平均值，初级产品 (%)

Simple mean bound rate is the unweighted average of all the lines in the tariff schedule in which bound rates have been set. Bound rates result from trade negotiations incorporated into a country's schedule of concessions and are thus enforceable. Primary products are commodities classified in SITC revision 3 sections 0-4 plus division 68 (nonferrous metals).