Thanks John
Very interesting scenario. I don't think I realized that the difference in real life was in fact so small between the two versions. That a C-2 could be upgraded to a C-4 seems very likely while making a D into an E would be a lot more difficult.
Wonder why they in fact changed the sub-version title in this case and not just continued with a D-x?
Anyway your explanation is very much plausible and I have made an explicit note about it in relevant places.
May I ask if this is the first D-3 WNr that this change can be noticed or are there any lower (or indeed higher) WNrs where this also can be seen?
Thanks again John for taking the time to enlighten all of us
Very much appreciated!!
Cheers
Stig