W3C:

2005-07-07: The XML Core Working Group has released a Last Call Working Draft of XML Linking Language (XLink) Version 1.1. Comments are welcome through 26 August. The XLink 1.1 language allows elements to be inserted into XML documents in order to create and describe links between resources. It uses XML syntax to create structures that can describe links similar to the simple unidirectional hyperlinks of today’s HTML, as well as more sophisticated links. Visit the XML home page. (News archive)