that IS UK only with tmc enabled at that price tt, I dont need europe cus i dont drive their on a daily basis!, is it true though that the TMC feature doesnt work in the uk , only in europe. (tmc is like trafficmaster, tells of any delays on the screen) incase you didnt know, which i expect you do! 
Yebut - the issue I was trying to establish was not the actual country coverage, but the disc format.
The discs themselves hold the software (as well as the digital mapping and POIs) to enable the navigation system to run. If you have a CD based navigation system, then it won't run with a DVD-ROM disc, and vice-versa. My S4 has the CD based RNS-D, and SWMBOs GTI has the DVD based RNS-E, and the discs are not interchangable. Even different edition years have different levels of software to drive the head unit. Take a look at
http://www.navshop.com/ and you will see what I mean.
Oh, I do know what TMC is: Traffic Message Channel - the data is broadcast in the UK, but the adaptive part of it has never been enabled, thanks to the incompetence of the Highways Agency who were supposed to sort it out, but never did. It works boomin' marvelous in mainland Europe, even in my S4, it was superb at automatically re-routing, and giving spot-on info regarding delays, and the exact junctions. The DVD system in the GTI was a quantum leap again.
