For each AOC (or equivalent), specifications exist detailing the practices that are allowed or not allowed in each appellation zone. Similarly, the analytical characteristics of the finished wine are also specified. The list of authorized grape varieties is also included.
There are some instances where different categories of varietal exist: the main grape varieties and the additional grape varieties (also called accessory grape varieties). The latter are planted in a limited proportion on the vineyard and there is also a maximum percentage allowed in the final wine blend(s).
In some regions of the world, the specifications are less restrictive for certain aspects, including grape varieties. In these instances, the production objectives and the best agronomic suitability as well as the intrinsic quality of the grape variety must be taken into account.