当然，保留这类数据的一个缺点是占用磁盘空间，但在许多情况下，在需要时能够使用这些数据的优点远大于其磁盘空间成本。
The drawback of keeping this much data is, of course, disk space, but the benefit of having this data available when needed outweighs the cost in most cases.
保留到反射对象的引用会造成这些类保持为活动状态并继续占用空间。
Holding references to the reflecting objects causes these classes to stay alive and continue occupying space.
名称空间建议书文档本身将这些声明当作保留属性，这些声明长得足以介绍它们。
The Namespaces Recommendation document itself refers to these declarations as reserved attributes long enough to introduce them.
应用推荐