Slightly off topic, but are we entirely sure the civil part of the registration is worthy of inclusion?
Everything I've seen on these rascals leans solely to the military serial anyway?
They're not just either delivery registrations relating to some odd Singapore import legality are they (wouldn't be the first time they've bee somewhat tetchy over military purchases)??
Maybe we just go with the military serial alone if that's what's only carried on the aircraft?
In this case, the assumption appears to be that, since Singapore civil codes are algorithmically related to registrations, then the same algorithm can be applied in reverse to a military hex code to produce a "civil" registration".
I don't know whether that's a valid assumption or not, I only know that I've never come across Singapore civil registrations in the 9V-Y** sequence, and there is certainly no sign of a civil reg painted on the aircraft.
However whether or not those PC-21s have civil registrations, the general issue remains - how to deal with aircraft that definitely do have (and wear) dual civil/military marks.
The Egyptian C-130s spring to mind, for example.
