To venture into Naval parlance, "Belay my last pipe !" - further investigation shows that a form of RDS is operative on DAB. Two Roberts radios in the bedroom both show 'rolling' info detail on R4 and 3. However the downstairs Bose remains stubbornly blank. So far, nothing useful on the Bose site, so I shall continue the search. Any clues or pointers most welcome.
Treaders - the other 'oddity' of the DAB output is the initial 'packet' repeat, on switch on.- at least, I'm assuming that it's to do with DAB being transmitted in 'packet' form, but the whole 'techie' bit is beyond my ken.