With MicroStation CONNECT, we can attach Item Type data to a DGN element. Those data are user-defined and can be used subsequently to extract business information from a DGN model.
What happens when an element is edited? If the element is deleted, is seems reasonable that the Item Type data should also be deleted. But what happens if an element is copied or split in some way: say a multi-line is dropped, or a shape is divided in two. Should the Item Type data be copied to the components of that dropped multi-line, or applied to both halves of the divided shape? Or, should the Item Type data be deleted?
Different usages will have different requirements. That calls for a user-defined propagation policy for Item Type data. That policy is analogous to the propagation policy already in place for MicroStation Named Groups.