A discriminatory tax ; preferential tariff rates ; preferential treatment ; a preferential shop gives priority or advantage to union members in hiring or promoting .

优惠税；优惠 税率；优惠待遇；一家对 工会成员在雇用和提升上给予优先权或好处的优惠商店。

Based on the difference of economic integration it is divided into six types : special tariff zone free trade zone tariff union common market currency and economic liaison and complete economic integration .

根据经济一体化程度的不同，将其划分为特惠关税区、自由贸易区、 关税 同盟、共同市场、货币与经济联盟和完全的经济一体化等六种不同的类型。

Common external tariff rules of origin and competition rules are tools employed by customs union to protect its internal interests . Meanwhile multilateral disciplines restrict the protection in case to derogate the multilateral rules .

对外共同 关税、原产地规则和竞争规则是关税 同盟为了保护内部利益而经常采用的贸易限制工具，同样补偿性谈判和争端解决被认为是维护多边纪律的重要制度。