XLink sophisticated hyperlinking:

• Links that allow you to choose multiple destinations
• Bidirectional links
• Links with special behaviours:
• Expand-in-place / Replace / Create new window
• Link on load / Link on user action
• Link databases
• See <http://www.xml.com/pub/a/2000/09/xlink/>

XPointer

• Provides access to arbitrary portions of XML resource
• See <http://www.w3.org/TR/xptr/>