In the USA, proof is a measure of the amount of absolute alcohol in distilled spirits, and is calculated as the number of parts of alcohol in 200 parts of beverage at 60 degrees Fahrenheit.
在美国，酒精度是纯酒精在蒸馏酒中的含量，计为60华氏度下纯酒精的1/200。
参考文献：
Factline on Alcohol Doses, Measurements, and Blood Alcohol Levels
