Bit of an update on this. I found a VM with (I think) v28 DATEN files.
MSV80.ATS has :
VW52;;;7580866;SE
MSV80.DAT
7580866,7568560,7581123,A,7580865DA,0FFFFFFFFFD,00 0,1 1
...all of which appear to match the DME label exactly
Bottom label
Correct VIN
7568566
7581123 (part number repeated)
7580866 (repeated from the top label)
So 7580866 for the ZUSB Nr and the data file ie map is "less by 1". All lines up.
Also the 0049QK0MG10S reference appears in the 7580865.0da so it all points to matching numbers etc.
Only number I don't have a reference to is 7568566 on the label.
As I'm still not convinced I have the right version I'm probably going to attempt to flash that older version I think to get me back to square one. I still have the DME coding error and whilst the car drives quite well, I would prefer to know it's the right version. Then I can upgrade from there again. Finally I also want to look at upgrading the EGS which is the whole reason I started on this (downshifts can be quite clunky)
Wish me luck....
