http://karmalib.sourceforge.net/docs/protocol.php

http://www.cliff.biffle.org/software/pearl/docs.php

http://www.freakysoft.de/html/libkarma/

Honestly, I've never known why Rio won't open up the protocol. It seems to me to be totally counterintuitive. I don't personally think there's really anything in the protocol that is all that proprietary and it would just allow people to write cool apps. It only helped the Empeg, IMHO, to open up the protocol specs. Every couple months I request that they just open source RMML. Oh well.