Cross plug-in references in the Eclipse help

Extending the Eclipse help is simply writing html pages. And linking between those pages is easy as long as the pages all reside in the same plug-in. Cross plug-in references (linking from plug-in A help page to plug-in B help page) requires just a little bit more information in the link:

<a href="PLUGINS_ROOT/plug-in-id/path/page.html">My other plug-in</a>

PLUGINS_ROOT will be replaced automatically during runtime. All you have to do is to replace the plug-in-id with the targets plug-in id and fill in the complete path to the html file. Even $nl$ parameters are possible here.