Railcom is a bi-directional DCC communications developed by Lenz. I know that Lenz 'Gold' and some Zimo decoders support it.
I do not know what Rocco or Fleischmann may have in their engines. I think you will need to contact them. There does not appear to be a lot of Railcom support out there. What are you trying to do using Railcom? You need more than just the decoders to make this work....
Jim
Modeling BNSF and Milwaukee Road in SW Wisconsin
Do anybody knows if the ROCCO / FLEISCHMANN locos have railcom decoders?