The common market organisation (CMO) in wine (“Gemeinsame Marktorganisation GMO für Wein”), valid since 1 August 2009, is mostly referred to as EU wine market regulation, and prescribes the following quality classifications: “Wine without protected designation of origin“ (subdivided into “wine“ and “wine with indication of grape variety and/or indication of vintage”) and “wine with protected designation of origin” (subdivided into “Wine with a protected geographical indication” (PGI) (“Wein mit geschützter geographischer Angabe“ (g.g.A.)) and  “Wine with a protected designation of origin” (PDO) (“Weine mit geschützter Ursprungsbezeichnung” (g.U.)).

The two categories of geographical indications differ insofar as PDO products are reserved for products produced, processed and prepared in a given geographical area using recognised know-how. In comparison to that PGI states that a connection with the region must exist on at least one stage of production, processing or preparation.

In case of the former indication the connection with the respective area is consequently closer.
According to the European and national wine law the winegrowing area of the Rheingau is a ”protected designation of origin“ (PGO).

Quality wines and Prädikatsweine are produced almost exclusively in the Rheingau. Only these wines may bear the appellation – in the sense of the COM in wine – “protected designation of origin Rheingau“ (“geschützte Ursprungsbezeichnung Rheingau”).

According to the European wine law Rheingau Landwein and Landwein Rhein are among the wines with “protected geographical indication (PGI)“; however, they play only a minor role in the Rheingau.

In case of ”g.U. Rheingau“ (“PGO Rheingau”) wines a distinction is made between the following quality classes and quality levels:

Qualitätsweine (Q.b.A.) (“Q.b.A. = Qualitätswein bestimmter Anbaugebiete, Quality wines produced in specified regions = p.s.r.”) are by 100% from the Rheingau. Depending on the type of wine and the grape variety they fulfil a minimum quality of the grape harvest (must weight) as well as certain analytical maximum and minimum values. Like Landweine quality wines may be enriched (chaptalised). The addition of sugar prior to fermentation is legally limited.

Since the vintage 2000 quality wines can also be designated with the terms ”Classic“ and ”Selection“.

All quality wines and Prädikatsweine may only be used and marketed after they have passed the quality wine test and given an official approval number (in German: “AP-Nummer”).

... the highest demands apply with respect to grape variety, ripeness, harmony, and elegance. These wines may not be chaptalised. There are six different Prädikate (wine distinctions), with different minimum must weights depending on the type of wine and the grape variety.

The Prädikate in ascending order:

Kabinett: Fine, elegant wines from ripe grapes usually with a lower alcohol content.

Spätlese: Ripe, elegant wines with fine fruit nuances which can be harvested a little later.

Auslese: Noble wines from fully ripe grapes, unripe grapes are eliminated.

Beerenauslese: Full, fruity wines made from overripe grapes infested with noble rot; the fungus Botrytis (noble rot) contributes to the quality; such wines cannot be harvested each year, they can be stored over decades.

Trockenbeerenauslese: made from raisin-like shrivelled grapes infested with noble rot, the Trockenbeerenauslese is the apex of the quality pyramid. Sweet and honey-like, it stands for extreme longevity over many decades.

Eiswein: Made from grapes that reached the same minimum must weight as Beerenauslese, but which were harvested while still frozen at temperatures below minus 7° Celcius, and which are pressed while still frozen so that only fruit concentrate is squeezed.