Due to the Conegliano Valdobbiadene’s complex geologic history, there is tremendous diversity of terroir between the eastern and western portions of the zone and even different sub zones and parcels within the same area. For this reason, in 2009 a sub-category called RIVE was created, which indicates a Prosecco made of grapes from one of 43 registered geographic areas. In order to qualify as a Rive, the grapes have an even lower maximum yield and the wine must be vintage dated. It is also possible to find Prosecco DOCGs made entirely from grapes of a single vineyard parcel.