Rules of origin are the rules by which free trade agreements determine whether imports and exports enjoy preferential tariff rates. They exist to prevent nations not party to the agreement from disguising their goods as member-nation goods to take advantage of preferential tariffs.
「原產地規則」是自由貿易協定中，決定進出口產品是否能適用優惠關稅的門檻，這是為了避免第三國產品暗中「借道」自由貿易夥伴，而濫用這項優惠。