In this webinar, attorney and licensed customs broker Jack Shelton explains the fundamentals of a sales contract including why you need a written contract. Yes, a marketplace facilitator may have a physical presence in Arizona.The purpose of the CISG is to provide a modern, uniform and fair regime for contracts for the international sale of goods. Learn how to use the United Nations Convention on Contracts for the International Sale of. Goods! Therefore, the law governing the international sale of goods will often be the Convention. These forms are needed so the prime contractor can complete the MRRA Credit Request Application.