设置和读取CAD实体的扩展属性，多个链表的方式设置，指定名称和全部扩展属性的读取，很不错的资料，可以加深对链表的理解和CAD扩展属性的理解。个人编写。-Set CAD Entity XData and read CAD Entity XData.Use many resbuf to set.It can read specified name xdata and all xdata.It is very helpful to learn resbuf and CAD xdata.