There is a "secret menu" as described, but nothing there to the matter. My RNS 315 supports the DAB+ protocoll, not sure if TMC is included in DAB at all, but it should be...

And i dont know if the RNS-315 can listen to the FM antenna, while you are in DAB-mode?

It must be able to do dual DAB/FM scan simultaiousely, or at least load enough into cash to make the FM switch overlap.

I went to Sweden last weekend, and listened to FM: Sveriges Radio P3, then the TMC list populated and showed info. Maybe there are noe TMC info in DAB, only FM, and when listening to DAB the reciever does not fully listen to FM anableing the TMC output from the FM signal?

This is in deed strange...
Anyone who knows?