>>and then you can use it. Otherwise there is a potential for Internal Consistency Error.
>
>(1) it won't let you generate code if the database is not packed
>(2) I always use 'Clean up database' in the menu

Ok. I do remember we needed it because otherwise we often got that error. We have very complex relationship set in that database.
You can check my older threads on this topic (around 2005-2006).