I did some investigation regarding the MapID.
if you look at the folder structure under the NDS folder there are some .NDS files.
These are SQLite Database files. Looking at them using a DB browser might be helpful.
In root.nds there is a table called 'productDbTable'.
The field 'DataModelVersion' could be the MapID, in my Europe 2014 (2.3) map version it is 6095.
[Only registered and activated users can see links. Click Here To Register...]
Maybe some could try to generate .unl files using that ID.