This book is the fifth in the author's series devoted to developing his code theory. Bernstein (sociology of education, U. of London) presents the view that educators ought to study the nature of the relay that makes messages possible rather than merely the institutional and ideological base of pedagogic messages. He covers both the theory and the research behind his ideas, focusing on the importance of language and description. Annotation c. Book News, Inc., Portland, OR (booknews.com)