uniqueness element

基本解释

How do you define element uniqueness by multiple keys/attributes?
你如何通过多个键/属性定义元素的独特性？
At a deeper level, you may want to have constraints such as uniqueness of an element value, multiplicity of an element, or restriction of the values of an element.
在更高级别上，您可能希望使用限制，比如元素值的唯一性和某个元素的多样性，或限制元素的值。
The first part of the expression contains the namespace declarations (in this case, UBL 2.0 Invoice) and some auxiliary namespaces; these are used to ensure uniqueness of all element names used.
表达式的第一部分包含名称空间声明（在这里是 UBL 2.0 Invoice）和一些辅助名称空间；这些名称空间用于确保使用的所有元素名的惟一性。