British Telecom in the 70s and 80s filed patents in the US on the concept of cross-references in hypertext. In 2000 BT discovered one of these "Rembrandts in the Attic" (US 4,873,662) and decided to use it for squeezing money out of internet access providers. Litigation is beginning in 2002-02.

Note: this patent was applied for only in the US. According to current EPO practise it would however be grantable in Europe as well. As with the USPTO, the only thing that can prevent patents of this kind from being issued by the EPO are novelty destroying documents.

claims main claim A digital information storage, retrieval and display system comprising: a central computer means in which plural blocks of information are stored at respectively corresponding locations, each of which locations is designated by a predetermined address therein by means of which a block can be selected, each of said blocks comprising a first portion containing information for display and a second portion containing information not for display but including the complete address for each of plural other blocks of information; plural remote terminal means, each including (a) modem means for effecting input/output digital data communication with said central computer means via the telephone lines of a telephone network, (b) local memory for locally storing digital data representing at least the first portion of the selected block of information received via said modem means from the central computer, (c) display means for visually displaying such a locally stored first portion of a block of information and (d) key pad means connected to communicate data to at least said modem means for manual entry of keyed digital data; and further memory means being provided as a part of said central computer means for receiving and storing said second portion of the block of information selected by a particular terminal means in response to the selection of the block and when its respective first portion is transmitted to that terminal means for display, said central computer means utilizing keyed digital data from that particular terminal means of less extent than any one of said complete addresses for another block of information but nevertheless uniquely indicative of one of the complete addresses contained in said portion of the block of information which contains the first portion then being displayed by that particular terminal means for selectively accessing the part of said further memory means associated with that particular terminal means and for supplying the complete address of the next block of information which is to be retrieved for that particular terminal means and utilized for display purposes at that terminal means. Heise: BT-Gerichtsverhandlungen über Hyperlink-Patent Techlawjournal: details about the BT-Prodigy procedings BT Patent als E-Business-Killer? British Telecom accuses ISPs of patent infringement BT sues Prodigy BT goes to law over hyperlink patent BT pushes hyperlink patent BT launches US hyperlinks legal action Prodigy to fight BT's shameless hyperlinks patent lawsuit British Telecom Taking Prodigy To Court Over Hyperlinks BT sues Prodigy over US hyperlink patent