1. 预付费计量系统实体模型

        A generic entity model for electricity payment metering systems is shown in Figure 2.
Although it provides a limited perspective, it does serve to convey certain essential concepts.
        关于电子式预付费电表系统的实体模型见图 2。虽然有些局限，但是它传递了基本的概念。

2.1. 预付费计量系统实体模型的元素

        The essential entities of a payment metering system are:

• the Payment_Meter ;
• the Token_Carrier or Remote_Communication_Services providing the means to communicate with the Payment_Meter;
• the Meter_Operation providing the means to install a payment meter and to configure its variable;
• parameters;
• the Point_Of_Sale where a customer interfaces with the supplier to conduct transactions;
• the Customer_Information_System;
• the System_Interfaces where the va