Officially known as United Nations Convention on Contract for the International Sale of Good (CISG) is a 1980 international treaty signed by over 80 countries, between them most leading trading nations, that amounts to a virtual commercial code for international sale of goods transactions, but exclude contracts for services. Although the CIS is the default body of contract law when both the exporter/seller and the importer/buyer are nationals of countries that have ratified it, parties may opt out by explicitly stating so in their international sale contract. A separate but related agreement, the United Nations Convention on the Limitation Period of the International Sale of Gods, covers time limits for seller and buyer claims of breach, termination, or invalidity arising from contracts of international sale of goods. Parties desiring to opt out of either convention should specify the body of law they wish to use instead. Care must be taken when doing so, as the conventions may be part o the body of law the parties wish to use. See international sale contract. Website.