For example, it is possible to express that InvoiceType (type of Invoice number) cannot be subtyped, that is, no one can define a new version of InvoiceType.
These basic types can themselves be subtyped to define new kinds of content, and it’s typical to define subtypes of a document for a specific kind of business.
这些基础类型自身可以用作子类型来定义一种新的内容,最典型的是为某种特定业务定义一个文档的子类型。
3
Step through the creation of subtyped entities and three service types that may consume them (add, update, and inquiry by identifier) with performance considerations in mind.