Hello Alain,
Fascinating to read that someone after more than 800 postings seems not to know that such a code is called a Stammkennzeichen and (normally) can not be linked to a specific unit
unless it pops up somewhere in a flight log book of a pilot, known to be flying for a specific unit.
I assume that you fell victim to one of the famous and most tasteful Belgian beers (which is no shame at all)!
All the best, Marcel
www.fliegerhorst-venlo.net