使用C语言的宏实现的面对对象编程，很有意思，文档齐全-Using the C language macros implemented object-oriented programming, is very interesting, the document is complete

OPC 历史数据访问代码从OOPC基金会下载的，非常有帮助！ -OPC Historical Data Access code downloaded from the OOPC Foundation, very helpful!