from this use case, I see three Significant data points, Product, store, and Purchase. IracKMyBuys of course tracks which products are purchased, and for which stores. Though not explicitly mentioned, it stands to reason that each Purchase is associated with an Account, since we need to store who is actually making the purchase. Recall that we previously dismvered the Account entity from the first use case, Account Signup/Installation. I now have enough information to create some structural database rules. I'll number them so that they can later be referred to by number