Hypertext Model Structures

Within the reference model, the hypertext model structure form is based on individual discretion, like graph-based, text-based, etc. It does not have to be homogeneous in form, but also heterogeneous structure, and also can be either dynamic or static form.

The Abstract Component Level

In this level context’s there is no dependency between the representations, it will be made at the lower level of abstraction. The representation presents the components that will be associated with one-another to form the hypertext. The contents that will be viewed by the reader are separated with the collections of link starter (such as buttons, etc) that will be selected by the reader when they are moving within the hypertext.

The level consists of four sublevel, they are: structure, abstract contents, abstract buttons and abstract containers.

Structure

The structure of the hypertext can be chosen arbitrarily. The Trellis system, by Stotts and Furuta, uses a Petri net structure, which provides automaton semantics as well as the network representation. The hypertext structure is not limited to networks; descriptions which are constrained can be used as well. The elements of the structure in the graph based approach are not required to be fully connected. This structure is just provides a placeholders that will be associated with the hypertext’s content and it describes relationships that exist among these placeholders.

Abstract contents

The abstract content is of arbitrary form. This is where the contents of the hypertext are located. The content may be textual, graphical, animated, audio, video or other material. It also can be the result of computation or specified directly. If without links, it may incorporate markers that defined locations for mappings of the links and their presentations that occur in the lower levels of the model. The content may be described in a form that is independent of the eventual characteristics of its display or it may be described in a form that is highly dependent on the eventual display.

The abstract buttons

The relationships among content elements can be displayed using the abstract buttons. This sub level may have content and associated type. When the button is displayed, the content then shown and the associated type describe how the button is displayed and other characteristic of its behavior regarding display and selection. The content may be statically defined or computed.

The abstract containers

The abstract containers are an abstraction of how the pieces of the hypertext will be combined when shown to the reader and not of what is in the hypertext.

The Abstract Hypertext Level

To form a hypertext, the elements of the abstract component level are necessary to be connected together. However, the elements are not connected together, yet in the abstract component level. It will be performed in this level, the abstract hypertext level, but the abstract hypertext level does not describe how these connections will be presented within the display of the hypertext, the concrete context level will be responsible for that.

The content-structure associations

In this association the elements from the abstract components level are associated together. The elements are structure and abstract content. The association naturally is to map the content elements to the nodes. The Trellis model/r-model imposes no restriction on the kind of mappings that are permissible.

The button-structure associations

The button-structure associations map the structure's relationship and abstract buttons. In the graph-based system, the association naturally is to map the abstract buttons to arcs in the graph. The one to one mapping or one to many mapping is allowed in this associations.

The container-structure associations

The container-structure associations describe the association of the structure, or portions of the structure, to one or more abstract containers. Grouping element of the structure is allowed in this association, such as grouping text and graphics so they can be displayed together in a single window. This association also allows the partitioning of the subsequent display of the hypertext into one or more possible overlapping pieces.