Many people here doesn't seem to get what the author is talking about. If I link to http://www.google.com http://www.google.com, the content might have changed

Many people here doesn't seem to get what the author is talking about. If I link to http://www.google.com http://www.google.com, the content might have changed when you open it. The URL always references the state of the resource at the time of retrieval, which is not always the intention. REVAT is just a proposed way to reference a specific state of a resource.