--- In IBObjects@y..., Geoff Worboys <geoff@t...> wrote:

>
> But it seems that either we are not talking about an enforced
> foreign key, or you are applying your own enforcement via triggers.
> This is not typical, although many of us do still write (at least
> some) trigger enforced relationships NULLs are the typical

mechanism

> to support empty relationships (so you an use declarative NOT NULL
> to enforce mandatory relationships).

I take everything back (which is hard since I wrote alot!)

I looked in the IB docs under foreign keys and RI, and sure enough
integer key-fields certainly do hold the value of NULL. One of the
RI options is indeed to set all foreign keys of the child tables to
NULL.

I guess I was stuck on the true sense of an integral type where it
must hold a valid integer (0 or otherwise). (I minored in
mathematics and look where it got me!)
I have now changed my lookupcombo fields to accept null with no
DefaultValue.

Thank you, Marco and Geoff for steering me along the right path.

Eric.