>Intra-entity RI belongs in the Data Tier, Inter-entity RI belongs in the Business Logic Tier.

That is an excellent way to put it. Couldn't have said it better myself (obviously... <s>)

> My question is, though, what do you call an "entity" - that is, where do you
> draw the line? For example, it seems clear that phone numbers are attributes
> of Employees, i.e. part of the same entity. However, Employees are part of a
> Company, which may be part of a Conglomerate, which is part of the NYSE, etc. etc.

I just posted another reply to Bob Archer (Message #295632) that deals with exactly that issue.

Markus