Tech Geek, that is standard behaviour of WikiForum http://manual.wikiation.nl/Level_2_wikiforum
It is used in its own namespace but could be used instead of the discussion page as well. It give much more structure and enforce respectation the time depending structure of the thread.
It is propriety software. It is part of Wikibox Blue of Wikiation
This very valueble for my Organisation. I have many doubts, but maybe I consider to make it Open Source. I will start a new thread about this.
Bernard Hulsman