Just an FYI for those interested in sub-types and certifications (ref FAA & EASA )
TCDS No. EASA.A.084
ATR 42-500 ‘600 version’ or ATR-500(600)
(1) ATR 42-500 ‘600 version‘ is the designation to identify ATR 42-500 aircraft
models having received the ATR New Avionic Suite (NAS) modification, also
named as ‘Glass Cockpit‘, and a batch of associated ATR (major & minor) modifications.
ATR 42-500 ‘600 version’ aircraft is not considered as new aircraft model nor variant.
ATR 42-600 is the commercial designation of the ATR 42-500 aircraft model
fitted with NAS modification.
ATR-42-600 Close enough for photogs, : and such,
but not official stuff as logbooks, and FAA/EASA complaice. :-)
(same for the -72 series as well)