OCL is planned to be used for the refapp concepts management. There was an issue in OCL export code, which prevented us from using it. I may have fixed it as a side effect of my recent work in OCL, which I need to verify. I am planning to move the refapp to OCL within a month, but most likely merge it after RA 2.7 release so it is properly tested and released with RA 2.8.
I haven't used the subscription module for a while. I recently heard about a connection issue with the latest OCL, which needs to be fixed. The module will be used by the refapp to install concepts from an ocl export bundled with RA (offline) and then you can set it up to get updates (online).