VB6接口、对象比较等

http://msdn2.microsoft.com/zh-cn/library/c8shwxa5.aspx msdn
http://www.bccn.net/Article/kfyy/vb/jc/200511/1204.html 类型
http://www.mndsoft.com/blog/article.asp?id=662 数据类型vartype
http://blog.csdn.net/lion_wing/archive/2006/02/07/593791.aspx 接口继承
http://topic.csdn.net/t/20040907/22/3349985.html 接口继承