The hierarchical class diagram demonstrates a way to discover an entire class inheritance relationship within a project or a work set.

层级类图代表着一种方式，该方式能发现在一个项目或工作集中，发现整个类间的层次关系。

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And through HIPO diagram, the hierarchical structure and scheduling relationship of all models in the system from the macro and micro aspects are described.

并通过系统的HIPO图从宏观和微观两方面描述了待实现的系统各模块之间的层次结构和调用关系。

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