note: browsing through the web by following one link after another is known as "surfing the web" ...
the idea behind the described experiment is to let the server make suggestions to the reader so she or he might find the appropriate path to the information she or he is looking for faster and without detours.
the suggestions on the server are generated by programs written in LISP and are provided as HTML documents. the LISP programs are controlled by "variables" that the user defines. a simple example would be a number of documents about the same subject, written in different languages. by setting a "language variable" the user can select her or his preferred language. another implementation would be that users might get different information depending on their knowledge of the subject. a "novice" would get an overview while a "senior" would get more detailed information.
this additional functionality has been implemented by adding new features to the server and by extending the HTML specifications. the problem with such extensions is that - as long as they are not implemented as part of the standard - they depend on a certain version of the server, or they have to be implemented in each new release of the server. i consider this an important drawback.