Starting with version 2.5, activeRenderer provides a way to include part of the outline's content into the URL specifying a transcluding link.
If you think this is gibberish...
You're probably right.
A small example will probably make things clearer, at least if you are reading this directly on the activeRenderer News site. Click on the 'page' wedge icon to the left of the next paragraph to learn what MSDN can report about activeRenderer.
activeRenderer
The URL of the link attached to the previous node looks like this:
http://beta.search.msn.com/results.aspx?q=##self##
##self## is a link macro that references the current node's textual content.
Link macros come in several flavors besides ##self##. They are useful as search requests arguments to specify richer outline links. Learn more about link macros in activeRenderer's Tutorial 9.



