That way the user always has the same set of tools to use on every site. We need to define a small number of standardized navigational dimensions and a standard way of encoding them. This would remove much of the navigation overhead from page designs. There is already a beginning to this in terms of the HTML LINK tags that can optionally be included in the page headers. Unfortunately these tags are currently only used by the iCab browser for the Macintosh.
All navigational power is assigned to the client interface as opposed to residing in each message.