如果您将一个元素移动到一个新添加的包中时，或者将源代码中元素(类，类属性，或者接口)重命名时，元素就像它是新添加的那样进行处理。
If you move an element into a newly added package, or rename an element in the source code (class, class attribute, or interface), the element is treated as if it were newly added.
有这样一条经验可以遵循，服务器类属于一个域包并且常常会形成它们自己的域包，因为它们是应用程序里消息流的最后一站。
One rule of thumb is that server classes belong in a domain package and will often form their own domain packages because they are the last stop for message flow within an application.
最后，定义模块设置了类属性，以声明新元素是从topicref派生的，并由howto包提供。
Finally, the definition module sets the class attribute to declare that the new elements derive from topicref and are provided by the howto package.
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