hey,
the A330/A340's have the derate climb function ( D1, D2). depending on the gross weight you enter the derate which in turn reduces the thrust for the climb. hence saving engine life but increasing your fuel burnt.
as for the 320 we didnt have this function on our acfts.
we use it on the 330's cause the acft is overpowered and never on the 340-300 since its powered by 4 hair driers( CFM enggines).
see ya.