When reading a linear text, cohesion is maintained through a rich mesh of contextual clues. Words and phrases refer both backwards and forwards to other text. This occurs at all scales, from the local (within one sentence) to the global (between books). As non-linear text, hypertext disrupts this cohesion. An extended rhetoric is required for writing in hyperspace.
In Mapping Hypertext, Horn notes eight rhetorical devices common to linear text which may be lost in hypertext. We rewrite his list, with examples, as follows:
Correct chunking of nodes can prevent context clues from going missing. For example, referring to a person as "she" requires an earlier proper noun in the same node to provide for readers who have not read the "previous" node. However, this requirement can lead to repetition of text or links. This becomes a design decision. Should "JPEG" be explained every time it is used? Should every instance of the term be linked to an explanation? Should only the "first" instance be explained? If so, can we assume the reader will encounter one particular node first?
This problem becomes greater if the hyperbook is viewed at a larger scale. Begeman and Conklin have commented on the difficulty of shaping an argument in a hypertext setting:
Traditional linear text provides a continuous, unwinding context thread as ideas are proposed and discussed--a context that the writer constructs to guide you to the salient points and away from the irrelevant ones. Indeed, a good writer anticipates questions and confusions that you may encounter and carefully crafts the text to prevent them.
The hypertext [...] author, however, is encouraged to make discrete points and separate them from their context. [...] Even the careful author [...] may not anticipate all the routes to a given node, and so may fail to develop the context sufficiently to clarify its contents. (260)
The authors recommend the use of paths to "linearize a network's segments sufficiently to provide context" (260).
Of course, contextual ambiguity can be exploited. Hypertext opens up intriguing possibilities for the author willing to forego standard devices and the safety of a highly closed contextual mesh.