I just looked at the Gateway manual to see what setup codes they recommend, and compared them to setup codes in the JP1 Lookup Tool. The first digit of some of the 5 digit setup codes are different, but I know that UEI really uses 4 digit codes, with the 1st digit meaning device type, and the meaning of that first digit can vary.

Once it was clear that the setup codes are from UEI, then the Lookup Tool also tells us the protocol and device number. Function numbers too, if you grab RemoteMaster from the JP1 site, and translate the EFCs.