Network: There's more than one way to link your hypertext

THE H in HTML stands for Hypertext. Although it may seem like a new concept, hypertext is an idea (it in fact started out as a philosophical dissertation) that was first proposed in the Sixties by Ted Nelson. He developed a philosophy around the idea that our comprehension of what we read is dependent not only on the knowledge of the author, but also on the knowledge of the reader. Nelson realised that for readers to understand a text fully, they needed a way to explore the "metatext" of the document - the details of any reference found within the text. At the time, this seemed impossible. Although you could add footnotes, there was only so much room on the printed page. Even then, footnotes could only go so far.

Today we take the idea of hypertext for granted. We link our documents together in the huge metatext of the Web with hardly a thought to the power this medium gives us to change the very nature of the way in which we communicate and think.

In the past, I have discussed what hypertext is (www.independent. co.uk/net/980210ne/story5.html) and ways of designing better hypertexts (www.independent.co.uk/net/980217ne/story4.html). One problem that I encounter when trying to design hypertexts is understanding how to structure the content and links. This week, I would like to explain four ways I have found to structure hypertextual links. Some methods might seem strange and counterintuitive, but they have the potential to open new ways of communicating and understanding information. You can check out examples of these different forms of hypertextual linking at my website (www.webbedenvironments.com/ examples/61.html).

Linear linking structure: In a way, linear linking, where there is only a single link that takes the reader to the "next" page of content, is not really hypertextual. Although it allows the visitor to move between different pages, this merely mimics pages of a book and prevents the visitor from exploring content except in the order you want them to see it. This defeats the purpose of having a medium that should free readers of the need to follow a path predetermined by the author. Still, for portraying certain kinds of information - for example, where what is being presented builds upon information that has to have been previously viewed - this may be your best solution.

Related linking structure: This is probably the most common form of linking on the Web and is the style that most closely mimics footnotes. With related links, the author sets up hypertextual relations to other Web pages or sites that contain additional information about the content being presented. The author can add any number of links from their content to other supporting content, but the links must be selected carefully so as not to send the reader off on a wild goose chase.

Tree linking structure: The traditional method to add structure to your site beyond a straight line is to create a tree structure, where the visitor can select their path through your information. Hypertextual tree structures remind me of those "choose your own adventure" books I read as a child. You would read a few pages, then choose the action of the protagonist. Depending on the action you chose, you would go to different pages. The narrative was, in effect, linear, but readers could choose the path that suited them best. For websites, this works by giving the reader several links to choose from on a page. These links take them to one of many possible "next" pages rather than the single next page of the linear link structure. They then proceed through the site, weaving their own web.

Fractal linking structure: With the tree linking structure, we think of each page in a website as a discreet "bundle" of information, complete in and of itself, linked to other discreet bundles. With fractal linking, however, a summary of the information (or abstract) is first presented. Each portion of the content will then contain a link to the same information, but in greater detail. Then, each portion of content on those pages will contain links to increasingly detailed explanations of what was presented on the previous page.

Imagine you are writing a fictional story. Normally you would write out the story from beginning to end in a linear fashion. However, if you were to write the story in a fractal fashion, you would write out the entire story in a few short paragraphs, not going into much detail on any particular point in the story. A reader can read this to get an overview of what has happened. Let's then say that you mention a conversation between two characters in one of the paragraphs of your story. The reader can click on a link and read the conversation. Within that conversation, then, let's say you mention some object that your characters were discussing. The reader could click on a link to see a more detailed description of the object. As the reader moves away from the first "page" of the story, the story becomes increasingly detailed.

This system can work well for presenting highly detailed business reports and scientific studies. The reader can read the abstract to get the full (but limited) report and then follow links to magnify particular portions of the report for a more thorough explanation of the content. The resolution of the information is left to the author.

Jason Cranford Teague (jason@ webbedenvironments.com) is the author of `DHTML for the World Wide Web'. Visit his website, Webbed Environments, (www.webbed environments.com), for an archive of this column