If you are thinking of adding these doors to existing cupboards then I don't know quite what you mean.
As far as I can see, our doors are simply hinged as normal, in three places on the tall cupboard doors, two on the small ones. The only difference from other doors is that they extend above the normal cupboard. For this top 'compartment', here is no backing, the 'back' is the wall behind it, though one might want something different in a kitchen.

If you want to come and look, we don't charge very high prices for a viewing.