Digital radio (DAB)* - subchannel
Secondary components are usually named subchannels. These are temporary and can contain e.g. translations of the main programme into other languages.
If one or more subchannels are broadcast then the 
symbol is shown to the left of the channel name in the display screen. A subchannel is indicated by the - symbol appearing to the left of the channel name in the display screen.
Turn TUNE to access the subchannels.
Subchannels can only be accessed on the selected main channel and not on any other channel without selecting it.