IR codes for Marantz SR880 receiver

I am having a lot of trouble making sense of the Marantz IR codes for the SR880 AV receiver. Using EZ-Learn and the RC2000 remote that came with the Receiver, I am able to get Slink-e to control the receiver just fine. However, I am trying to make sense of the codes so that I can search for new codes (I'm specifically interested in finding additional multi-room mode codes) and am having very little luck. It seems that the codes almost match the RC5 system but not quite. Has anyone had better luck decoding these things?

Thanks,