This is my last post on this subject (hooray!).
Vehicles sold from 2006 on had to have a minimum of Euro 3, so their documents (inc V5 in UK) will show the Euro emissions standard, Euro 3 or Euro 4 at that time.
For vehicles sold prior to 2006, there was no requirement to meet the Euro emissions standard, (although many, like the petrol A2, did), therefore, their documentation, (inc V5 in UK) did not include the emissions standard.
In UK, if you have a pre 2006 car, which meets Euro 4, you ask the manufacturer for C of C and Euro 4 letter, then submit those documents to DVLA, (or the local authority who's Low Emissions Zone you wish to use without charge) and they will update their database, and you're good to (boldly) go.
No idea about the Germans (other foreign countries are available).
Mac.