To obtain DOC certification, there are a series of guidelines and rules for the production of red, white, rosé and sparkling wines, such as the analytical and organoleptic characteristics of the product, viticultural practices and the delimited zone, among others.
As for the grape varieties, one of the important points for this certification, not all are authorized and recommended for the production of wines in the DOC Bairrada.
Portaria 335/2015 is the guiding document for the Bairrada Denomination of Origin.
Consult them here: Bylaws