Moving Links Out of the Way

'Out-of-line' links

Easier to Manage Out-of-line links allow developers to centralize link descriptions. Instead of including the links in the document content, developers can create links that only describe the resources they connect, and let the application handle the actual connecting.
Requires Extra Processing While they make life easier for humans, out-of-line links require applications to do more work, possibly involving a second pass over the document structure to mark links.
'Resource' Mechanism The latest XLink draft uses 'resource' type child elements to identify in-line links. Resources are pretty much locators without an xlink:href attribute.