写出系统的功能，要求尽可能全面，至少应该描述至第二层。譬如，付款功能，需要根据付款的方式有下列子功能：现金付款、信用卡付款等。

详细列出各功能的详细要求，如输入要求，输出要求，实现要求，以及相关步骤。

给出系统边界的分析图

-write the function of the system, the requirements as comprehensive as possible, it should at least describe to the second layer. For example, the payment function, the need for payment of any of the following sub-functions : cash payments, credit card payments. Set out in detail the function of the detailed requirements, such as input, output, achieving requirements, and related steps. Is the analysis of the boundary map