My Windows application is single-user, so I started out using the
embedded version. However, I have an "admin" program and a "user"
program that both need to have the database open at the same time
(both admin and user programs run on the same machine). So I had to
abandon the embedded version and use the Superserver instead. Now I
need to know if TCP/IP is required with the client on the same
machine as the server with two programs running at the same time.

I'm led to believe from the docs that TCP/IP is NOT required because
of the CreateInternalWindow setting in firebird.conf. From the docs:

"CreateInternalWindow - The "Windows local" protocol uses a
hidden window for inter-process communication between the local
client and the server."

What's this "Windows local protocol"? Does it use SendMessage or
something and therefore TCP/IP isn't required with client and server
on the same machine.

Thanks,
Joe A.