This is a 3 levels master-details controls (bound) example, works also without scripts. A Regione contains Provincia(s) that contain Comune(s)

Regione *

AbruzzoBasilicataCalabriaCampaniaEmilia-RomagnaFriuli-Venezia GiuliaLazioLiguriaLombardiaMarcheMolisePiemontePugliaSardegnaSiciliaToscanaTrentino-Alto AdigeUmbriaValle d'AostaVeneto

Provincia *

Please select a Regione.

Comune *

Please select a Provincia.