|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
The attoliter or attolitre is a common metric unit of volume. It is equal to 10-21 cubic meters. Plural name is attoliters.
A hogshead (abbreviated "Hhd", plural "Hhds") is a large cask of liquid (or, less often, of a food commodity). More specifically, it refers to a specified volume, measured in either imperial or US customary measures, primarily applied to alcoholic beverages, such as wine, ale, or cider.