XML hyperlinking goes beyond basic HTML-style hyperlinking with a number of new features, including the ability to create "smart" links without a lot of hand-coded JavaScript. And in XML, links become objects in their own right and can thus be managed like any other objects.

The original linking specification--XLL, or XML Linking Language--is being split into two separate specs: XPointer and XLink.

XPointer: In HTML it's possible to link to the middle of a page only if the author of that page put an anchor tag there. With XPointer you'll be able to "address to" (not "link to") any part of someone else's text. It's easy to see how this ability would be useful in working with legal documents, scientific and academic papers, even W3C specifications!

XLink: When a user clicks an HTML hyperlink, the current Web page is replaced by the file being linked to. XLink lets Web builders add behaviors to links. Today, for example, you have to use a bit of JavaScript to make a link pop up a separate window, but XLink lets Web builders code links to perform a variety of actions, including popping up a menu of linking choices.

Another application of this technique might be to pop up a dialog box, perhaps an alert reminding users that they're about to update a database record. The link pop-up might require users to click a box to signify that they accept liability before proceeding. Today, this feature would take a boatload of scripting.

XML also lets Web builders create Extended Links that work sort of like a Web ring, which is a self-selected group of Web sites relating to the same topic that are navigated through a "next/previous" progression. For lists of related links too long for a pop-up menu, Web builders could create a linked list that changes from site to site and from page to page. Users could click an icon to automatically move to the next member of the ring. Today this capability would require CGI scripts, but Extended Links offers a standardized, nonproprietary method of creating relationships among resources.

There are additional issues still left to work out, especially in the area of behavior policies. There has to be a way to negotiate between the behavior a document's author recommends for a link, a user's preferences in regard to displaying link information, and policies as to if and when the user's desires should be overridden.

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