>Hi Jim,
>
>OK...let me think this through. Both tables store effective rate. This rate can change so you cannot maintain a simple key lookup. The same data is duplicated. Data-wise, is this not denormalization? I can see where in the entity models that the two physical fields may belong to different domains and, therefore, not falling into the category.

John,

Here's the thing, they do not both refer to teh effective date at the same point in time. One is current and the other is historical, that makes them non-redundant.