The Header is an optional element for carrying auxiliary information for authentication, transactions, and payments.
Header 是可选的元素，它携带认证、事务处理和支付的辅助信息。
2
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.
In recent years, commercial complex space design more and more emphasis on human nature, in shopping space, traffic space and the auxiliary space, with a human element.