You are the second kind person to point out the ' Cecilia Costello' example. You are in good company with John Bowden and Vic Shepherd who said the same. You are ahead of me with the terminology of the 'Picardy Third'. If you have a reference for me, this might save you some typing and some time. Fascinating to know of the Art Music parallel. Sorry I catch on a bit slowly. Could you help me a bit more by explaining why ending a D minor tune in F major, is not art music related, where as the 'Picardy third' is? Many thanks.