[Link: awe-europe.com]
Under the Denon  icon you'll find the official Denon pdf file which lists the codes.
I believe the cheapest  and most user friendly way to use these code is to buy a OARUSB04G (USA) or the sister remote URC-6440 (UK/Europe).  The codes aren't built in, but you can use the free RMIR software to install an upgrade which will shoot the codes.