|≈||approximately equal to|
|digits||indicates that digits repeat infinitely (e.g. 8.294 369 corresponds to 8.294 369 369 369 369 …)|
The butt was a measure of liquid volume equalling two hogsheads. This equated to 108 imperial gallons (490 l) for ale or 126 imperial gallons (570 l) for wine (also known as a pipe).
The barrel of oil equivalent (BOE) is a unit of energy based on the approximate energy released by burning one barrel (42 U.S. gallons or 158.9873 litres) of crude oil.