So... German wines eh? Bit complicated if you ask me - they are of course classified in several different ways - firstly basic quality - there are "Table Wines" and "Quality Wines" - table wines are placed in two categories - Deutscher Tafelwein (lowest classification from one of 4 designated regions) and then Landwein - similar to the French Vin de Pays from one of 17 regions which mut be shown on the label. Wines must be either "Trocken" (dry) or "Halbtrocken" (Off-Dry).
Quality Wines are also in two categories - QbA (Qualitatswein bestimmer Anbaugebiet) - which is literally wine from a designated quality region (an "Anbaugebiet). Often these wines will just show Qualitatswein on the label. To give you an idea Liebfraumilch fits in this category, as does Niersteiner Gutes Domtal and Piesporter Michelsberg (Hock is not a quality wine - it's a tafelwein.
QmP wines (Qualitatswein bestimmer Pradikat) which is again from a single Anbaugebiet but which also must come from particular district from within an Anbaugebiet (called a "Bereich").
QmP wines are then categorised by their "must weights" that is the specific gravity of the grape juice - which is in reality the amount of sugar in the juice.
So... when choosing a German wine - look for QmP on the label - it's no true guarantee of quality - but it will help it!