The Visible Hypertext Level

The details of the mapping from the concrete hypertext to the visible presentation of the hypertext for the reader are specified at this level. However, user interface details, such as the positioning and sizing of windows, are orthogonal to the r-model, and thus excluded from this (or any other) level.

An assumption in the r-model is that the underlying hypertext is to be permitted to be used in a distributed environment. The visible hypertext level reflects this assumption. Each visible HT segment is associated with a separate user and display. Each segment presents on or more of the active concrete windows to its viewer. The model does not prevent the display of a particular concrete window in more than one segment. Whether (and how) the effects of user interactions to one display may affect what is shown on other user displays is a property of the hypertext model, and not of the r-model.