闻亭公司培训DM642的内部资料一共有五天，里面包含讲解的ppt,文档，开发工具，课堂源码例子等。这是第四天内容.-Wintech DM642 training information, total of five parts, which contains explanations ppt, documentation, development tools, source code examples of class and so on.This is the 4th part.