Definition - What does Cask Number mean?
"Cask number," also known as "bin number," is a designation for special limited edition wines, or to differentiate or separate a lot or brand. Cask numbers are common in Australian wines. Originally, a cask number referred to a storage area of a winemaking cellar, but currently, they are more likely to reflect a consistent style of wine.
WineFrog explains Cask Number
Historically, Australian winemakers used to store their wine in numbered bins or casks within a wine cellar. Eventually, companies began to name particular wines after their numbered storage areas. Eventually, although the numbering tradition persisted, the cask number or bin number ceased to reflect the actual storage areas. Instead, numbers were either arbitrary codes referring to grape varietals, or were simply chosen at random.
Contrary to a common misconception, the presence of a cask number on a wine is not necessarily correlated with quality.