[Definition: Information about how to traverse a pair of resources, including the direction of traversal and possibly application behavior information as well, is called an arc]. If two arcs in a link specify the same pair of resources, but they switch places as starting and ending resources, then the link is multidirectional, which is not the same as merely "going back" after traversing a link.
XLink is a proposal for more powerful links between documents designed especially for use with XML documents. XLink achieves everything possible with HTML's URL-based hyperlinks and anchors. Beyond this, however, it supports multidirectional links where the links run in more than one direction. Any element can become a link, not just the A element. Links do not even have to be stored in the same file as the documents they connect. These features make XLinks more suitable not only for new uses, but for things that can be done only with considerable effort in HTML, such as cross-references, footnotes, end notes, interlinked data, and more.
[ November 14, 2002: Message edited by: Roseanne Zhang ]