Hello Brion,
[...]
Make a new extension and plug it in. There are a
couple of examples in
the 'extensions' module in CVS.
Thanks for your help. Everything works fine now. I have added my own markup.
(Just for the record:) The "trick" was to add my funtion in
$wgExtensionFunctions that initializes my extension and add a callback
via $wgParser->setHook that expects two parameters: name of markup and
function to be called with the content.
Patrick