Just a note about Programme Service
This is used to transmit the station name, and can be up to 8 characters long. The purpose of this so the listener can find out what they're listening to, without needing to know the frequency. If the station is stored as a preset, the name is stored along with it.
(For this reason, the RDS Forum has issued guidelines against dynamic PS messages - ie, flashing the station slogan one word at a time is not recommended in case "BEST" gets stored in the radio as part of "TODAY'S BEST MUSIC".)
Other RDS features:
Programme Type (PTY)
Each programme broadcast carries with it a type, such as
News, Current Affairs, Information, Sport or Education. See the full list.
These types let you see at a glance what kind of programming is currently being transmitted, and some sets let you scan the airwaves for a particular type of program - for example, hit a button to tune to the next Classical Music station.
Radio Text (RT)
This allows stations to send short messages about the current programme. It's a 32 or 64 character text string, and generally only home recievers will display it.
Enhanced Other Networks (EON)
This is used frequently by the BBC in the UK. If a listener was tuned to Radio 1, and a travel bulletin starts on a local BBC station, the radio will retune for the duration of the update. The transmitter can send Traffic, News and Weather flags, which the reciever can look out for.
This isn't always a perfect system - someone from BBC Radio Scotland explained to me that to send out a traffic flag, they press a button in the studio, which sends a signal to London, which tells the UK transmitter network that there's a traffic update, thereby introducing a staggering delay.