what is RARE organisation in the context of hypertext systems?
A little detective work reveals the following. From Chris Adie's Resume it seems that RARE is now called TERENA, which is "The Trans-European Research and Education Networking Association". Looking at the history of TERENA, reveals that RARE stands for "Réseaux Associés pour la Recherche Européenne", which is a little strange, as it is a Dutch organisation. 

Incidentally, one of my old pals used to work for TERENA.