To johnsfine,

Thank you, Thank you, Thank you!

I did exactly what you said, and it worked.
Nothing like clear, judgement-free technical help...

BTW, this 7DE1 and 7DE2 are discrete p-on/p-off codes for the Yamaha RX-777 receiver. Yamaha does not even show that receiver as having any "extended" codes at all, but after some digging, Yamaha tech support located the ONLY other Yamaha receiver ever made (RX-596) that uses the same basic IR code set as the RX-777. It turns out that the RX-596 extended codes DO work on the RX-777 as well.

My client is happy
I am happy

PS I'll post the entire mxd file for the Yamaha RX-777 and RX-596 in the files area soon.

Thanks again.

Audio Vision