A purchase order should have a shipTo element. A purchase order should have a billTo element. A purchase order should have an items element. A purchase order should have an orderDate attribute. A purchase order should have an shipDate element. The element is not expected at the top of a document. It should be in the body of a purchase order. An address should have a name. An address should have a street. An address should have a city. An address should have a state. An address should have a zip. The elements is not expected at the top of a document. They form part of an address. The items element can only contain item elements The item element should contain a product name. The item element should contain a quantity element The item element should contain a USPrice element. A comment should have no subelements A comment can only appear in an item or a purchase Order