For tax purposes, the sweet natural wines referred to in article 416, liqueur wines with a protected designation of origin, whose production is traditional and customary and which, subject to being subject to a control system offering guarantees equivalent to those required for natural sweet wines as regards the conditions of their production and marketing, have the following characteristics:
– have been produced directly by the harvesting producers from their grapes, at least 90% of which come from aromatic grape varieties;
– come from plots whose yield does not exceed 40 hectolitres per hectare of vines in production;
– be made from musts with an initial natural sugar content of at least 252 grams per litre;
– be obtained to the exclusion of any other enrichment by the addition of wine alcohol corresponding in pure alcohol to at least 5% of the volume of the musts used and at most the lower of the following two proportions:
Either 10% of the volume of the musts used;
Or 40% of the total alcoholic strength by volume of the finished product represented by the sum of the alcohol content acquired and the equivalent of the alcohol content in power calculated on the basis of 1% by volume of pure alcohol for 17.5 grams of residual sugar per litre.