Stack maps are graphic representations of the information outline showing key nodes or decision points. When used, it should be ever present and accessible from all parts of the materials. A number of interactive multimedia packages make efficient and effective use of this navigation tool. The following example is again from The Parliament Stack . Hierarchical - moving through the content in terms of main idea to minor idea or visually clicking to see what is a small component of the larger.
Most information has a subdivided or categorised structure.
Each element of this structure of the information metaphor should be able to be used in conjunction with navigation around the overall metaphor or information environment. The information structure is often chunked to allow the hierarchical classification or structuring of the information to be accessible level by level as the detail is revealed. This type of navigation form is often strongly associated with a metaphor to represent the information and then what might be called sub-metaphors or maintenance of the metaphor is used to continue the analogy of the metaphor to more detailed information levels. This type of hierarchical information access maintains the overall metaphor of the information landscape, and yet can also allows the designer to represent the more detailed information in a variety of forms such as textual, video or audio format rather than maintaining the higher level metaphor. A simple hierarchical menu structure is shown below.