The Concrete Hypertext Level

The concrete context level defines a set of concrete content elements in which a concrete representation of the content has been merged with concrete representations of the buttons. The concrete hypertext level maps those concrete representations into a set of windows for display. The mapping, which produces the concrete windows representation, also requires that link-based interrelationships among the windows be determined. For example, the process of following a link can result in several different display mappings: the display of the target of the link could replace the display of the source, could be shown in addition to the source, or could modify the display of the source, with both being shown in the same window.

When the concrete windows representation has been formed, the presentation of the hypertext has been determined but the details of how and where the windows are to be displayed has not. For example, multiple windows may be shown to a single reader on a display or a particular window may be shown to several readers simultaneously on separate displays. Also, a particular reader may have several displays at his disposal, and different displays may have equivalent but different means for achieving particular visual effects. (It is not uncommon to have a monochrome and a color screen side by side, both controlled by a single keyboard and mouse.) Such considerations are addressed in the visible hypertext level.