Unlike the UCC,the CISG requires new consideration to modify a contract.

CISG

The United Nations Convention on Contracts for the International Sale of Goods, a treaty that provides a uniform international sales law.

Consideration

Something of value exchanged between parties in a contract that is necessary for the agreement to be legally binding, such as money, services, or promises.

UCC

Short for Uniform Commercial Code, it is a set of laws that provide legal framework for commercial transactions in the United States.