FIGURE 2.11 combination of linear and hierarchical organization.

If you’ve just come down into this page fro

m an act summary, the context makes sense: Up means go back to the summary from which you just came.

The combination of linear and hierarchical documents works well as long as you have appropriate clues regarding context. Because the visitors can either move up and down or forward and backward, they can easily lose their mental positioning in the hierarchy when crossing hierarchical boundaries by moving forward or backward.

Suppose that you’re putting the Shakespeare play Macbeth online as set of web pages. In addition to the simple linear structure that the play provides, you can create a hierarchical table of contents and summary of each act lined to appropriate places within the text, similar to what is shown in figure 2.13.

FIGURE 2.12 Macbeth’s hierarchy.

Because this structure is both linear and   hierarchical, you provide links to go forward, backward, return to beginning, and up on each page of the script. But what is the context for going up?

But suppose that you go down from a summary and then go forward, crossing an act boundary (say from act 1to 2). Now what does up  mean? The fact that you’re moving up to a page you might not have seen before is disorienting given the nature of what you expect from a hierarchy. Up and down are supposed to be consistent.

Consider two possible solutions:

·         Do not allow forward and back links across hierarchical boundaries,. In this case, to read from act 1 to 2in Macbeth, you have to move up in the hierarchy and then back down into act 2.

·         Provide more context in the link text. Rather than just up or an icon for the link that moves up in the hierarchy, include a description of where the user is moving to