What does the number of puttonyos on tokaj wines mean?

Puttonyos is the unit given to denote the level of sugar and hence the sweetness of Hungarian dessert wine, called Tokaji (or tokay). It is traditionally measured by the number of hods of sweet botrytised or nobly rotted grapes (known as Aszú) added to a barrel of wine, but is now measured in grams of residual sugar. The puttony was actually the 25 kg basket or hod of Aszú grapes, and the more added to the barrel of wine, the sweeter the eventual wine. Measurement goes from 3 to 6 Puttonyos. A Tokaji made entirely from Aszú grapes is known as Eszencia.