"Everything involves structural hierarchy ... nothing can be understood without looking at it not only in isolation on its own level but also at both its internal structure and external relationships which simultaneously establish the larger structure and modify the smaller one."

Introduction

A current paradox of hypertext is that while there is considerable interest in the concept, and a number of fully implemented systems, there are few widely known hypertexts. The BBC Domesday videodisk project was certainly ambitious in terms of scope, but the high cost of the hardware restricted the uptake by individual schools and the patchy coverage limited the tasks for which the system was appropriate. Extensive experimental hypertexts have been developed in research and development departments in both the educational (Intermedia , Writing Environment) and private sector (KMS, Document Examiner, Thoth-II, NoteCards, gIBIS), but the market for 'published' hypertext has yet to take off. The vast majority of current hypertexts are small, with restricted functionality and of experimental interest rather than practical significance. However, while most hypertext systems require advanced workstations and are therefore unavailable to many people, Apple has been including a copy of their HyperCard application with every new Macintosh computer since 1987, and OWL's Guide system for the Macintosh has been available since 1985 (see Brown, 1987). Thus, the means for popular hypertext are gradually appearing.

The situation described above contrasts sharply with Ted Nelson's vision of the 'Docuverse' which contains every text (past and present) in hypertext format, uniquely referenced, universally available and easily included in new hypertexts (see Nelson, 1988). This scenario, even if only achieved in part, is likely to be a long way off and the difficulties that would have to be overcome are considerable. In Chapter 7 we describe, as a case study, the design and creation of a hypertext scientific journal from a paper original - putting into practice some of the ideas discussed in the earlier chapters. In this chapter we shall consider some of the practical problems , which are capable of reasonably clear definition, and then some of the pedagogical issues connected with alternative ways of structuring information.

It is convenient, and in keeping with Nelson's ambitions, to consider the practical problems according to whether existing texts are being transformed into hypertext or whether completely original hypertext is being created.