[Zope] 2.2.4 upgrade query

Further to my paniced posting earlier, I reinstalled 2.2.0, copied over my data.fs* and various products and everything fired up fine but i did one experiment (following on from Chris) - i didnt install zdiscussions. This resulted in major oids errors and my broken zclass as before/ install zdiscussions and bingo i am back in business. so. two questios: 1. why does my zclass appear to require zdiscussions when it is not based on it? 2. does 2.2.4 contain some parts of what was previously the standalone zdiscussions product? Is this an obsure backwarsd dependency break kindo of thing? I will stick to 2.2.0 for now, methinks. cheers Jonathan