130 Book reviews

carried out by a broker. The directory also provides raw data for those concerned with the history of online searching in the UK.

A new edition or a regular updating of this directory would be most welcome.

F. E. Wood Department of Information Studies Uniuersity of Shefjeld

John Williamson and Bob Raggett. Teletex. London: Eurodata Foundation, 1982. (Eurodata Foundation Guides for Managers). 69 pp. ISBN not given. E8.50.

It is curious that an organization devoted to the transfer of information should have such a cavalier attitude towards standard publishing practice: not only does this document lack an ISBN but the authors’ names do not appear on the title page. The first indication that the pamphlet is written by humans does not appear until page 9!

However, apart from these slight curiosities, what of the text? This is a timely introduction to one of those confusingly-named communication technology developments. Not ‘teletext’, nor even ‘Telex’ (although that comes close), but ‘Teletex’pa text communication service which, in all probability, will ultimately replace Telex. Not a set of equipment, as the authors point out, but:

. . a series of specifications which, if adhered to, will ensure compatibility between any manufacturer’s terminals for high speed exchange of alpha numeric information.’

The specifications referred to are those embodied in draft standards of the CCITT (Gomite Consultatif International Telegraphique et Telephonique) which specify basic terminal types, memory characteristics, message format, call identification, and transmission speed. This last element indicates why Teletex will replace Telex: the transmission speed of Teletex is 2400 bits per second, 30 times faster than Telex. Telex terminals are likely to survive for quite a long time, however, because interconnection with Teletex is possible.

After a brief introduction to the technical specifications the authors go on to describe the role of Teletex in office communications, its relationship to alternatives such as letter post, facsimile transmission, and computer mail (sometimes called ‘electronic mailbox’), network alternatives, PTT services, Teletex terminals, costs, impact on other services, case studies, and future developments. Each chapter is brief, well written, and designed for the target audience.

In all, this will be a useful little guide for managers and the price of L8.50 is not likely to be a deterrent in that market.

TDW

Thesaurus of ERIC descriptors (9th edn). Oryx Press, 1982. 569 pp. ISBN 0 89774 019 X. 922. J. Aitchison in association with 1. A. Smith and S. Thompson, (Compilers). An integrated classz$cation and thesaurus for youth ajfairs and related topics. National Youth Bureau, 1981. 530 pp. ISBN 0 86155 044 7. k50.

These two substantial thesauri are powerful expressions of the traditional belief