The Portuguese wine classifications, from lowest to highest are as follows:
1. Vinho de Mesa
Simple everyday table wine - not for export.
2. Vinho Regional
Regional wine - the equivalent of French Vin de Pays.
3. Indicação de Proveniência Regulamentada (IPR)
This is also known as Vinho de Qualidade Produzido em Região Determinada (VQPRD), and covers newer regions that are candidates for DOC, but that have not yet obtained that status.
4. Denominação de Origem Controlada (DOC)
This is the top tier of quality - the equivalent of France's Appellation Contrôlée. This classification covers the most established wine regions, and all DOC wines are subject to specific grape variety and ageing requirements.