2. Tree design
By determining how users will enter and exit the catalog, complex and intelligent conditional schemes are possible, especially if the Cookies capability is exercised. However, it is recommended that simplicity be used. Consumers will not make purchases if they can't navigate their way around the catalog.
It is important to remember that users will lose their session (and items in their shopping cart) if their browser does not accept cookies and they leave the site. Interchange addresses this problem by using the area and page tags. If you are using frames, source all frame panes containing Interchange links from an initial page served by Interchange. If you don't do this, the user may have multiple session IDs depending on which frame generated the link.
Note that Interchange can work properly even if the browser doesn't store cookies. In this situation Interchange inserts a session ID into each URL; if the ID is preserved as the user navigates from page to page the session will remain intact.