FIRM HETEROGENEITY, RULES OF ORIGIN, AND RULES OF CUMULATION*
研究原产地规则的限制性以及对角累积在缓解其保护主义内容中的作用，发现对角累积能放松原产地规则的限制性，导致最不具生产力的出口商停止出口。
This article sheds light on the restrictive nature of rules of origin (ROO) and on the role of diagonal cumulation in mitigating the protectionist content of ROO. Empirical evidence suggests that diagonal cumulation has beneficial effects on trade—particularly among spoke countries. We show that these patterns can be reconciled with a theoretical setting where heterogeneous firms buy intermediate inputs from domestic and foreign sources. The model finds that switching from bilateral to diagonal cumulation relaxes the restrictiveness of the ROO and leads the least productive exporters to stop exporting.