XANADU STRUCTURE

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98.11.17 ( d3

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XANADU® STRUCTURE "Xanadu" is a trademark of Project Xanadu, Sausalito CA. The myth: Xanadu is simply the dream of a universal populist publishing network, fulfilled by the World Wide Web. The truth: Xanadu is a specific structure which it is important to understand, which is PARTICULARLY WELL SUITED to electronic publishing networks.

The problems of the World Wide Web, which we foresaw--

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can be largely solved with xanalogical structure. (The unfortunate direction of Web standardization today-- toward sequence and hierarchy as embodied in XML-- will be seen as a temporary aberration.)

Like the Turing machine, xanalogical structure is an abstract idea which needs to be understood as a point of reference. And, even retrofitted to the Internet, it should provide a powerful remedy to the ills that now beset us.

THE FUNDAMENTAL VISUALIZATION OF XANADU

To understand this picture fully is basically to understand what xanalogical structure is about.

This illustrates

• One person's overall work and a specific article

• All the media in the world, and a specific collection

Each vertical line is a version-- that is, a map of the elements in a version. Each dot on the vertical line is an element.

Each line between the two versions shows an element which is the same, so the element is actually shown by both the line and the dots at its ends.

This indicates *transclusion*, the visible identity of an element which is in more than one place..

Maintaining and showing transclusions is the heart of xanalogical structure.

While links-- connections between things which are different-- has always been a part of the structure, they are not shown here to emphasize transclusion.

Xanalogical systems can be made large-grain or fine-grain.

LARGE-GRAIN XANALOGICAL SYSTEMS

Both the original xanalogical system (zipper lists, 1965) and the most recent design (ZigZag™) are large-grain.

In a large-grain xanalogical system, the elements in the illustration represent chunks-- paragraphs, sentences or cells.

FINE-GRAIN XANALOGICAL SYSTEMS

Xanalogical systems still under development (xoc86, xoc92 and OSMIC) are fine-grain. In a fine-grain xanalogical system, the elements are text characters, individual audio samples and video frames.