Intended to help human communications in the wide area which is being opened up by computers and by the new thinking they have generated, this encyclopaedia has been compiled with the help of specialists who are physicists, mathematicians, computer scientists, systems consultants, economists, psychologists, physiologists, documentalists, and students of linguistics. The central concept of the encyclopaedia is that of the signal. Each article is followed by a bibliography. An index/glossary is appended. (MF)