>>Yes, it was: I just wanted to get your attention, since you're the local VM
>>guru... :-)
>Please.... < s >

Hey, you should have thoughtthat before you wrote the book. :-)

>The third-tier are the components that do the actual reading/writing to the
> database.

Ok, so the "fourth tier" is the physical data? I realize that's not actually the case, but there is a kind of separation there.

So, would you typically have all the data access go through one class, that talks the all the tables, or would you have subclasses for each table?

One other thing I've been confused on: in a current project I'd like to model, we have an order table, an order line table, a payment table, and a payment line table. The payment line table refers to the invoice/order. That's four classes as well, right? with Orders and Payments having collection Properties containing line items?