sentences:  22 (1973) provides standards for measuring alcohol strength by volume and by mass.A preference for one method over the other is not stated in the document, but if alcohol strength by volume is used, it must be expressed as a percentage (%) of total volume, and the water/alcohol mixture must have a temperature of 20 °C (68 °F) when measurement is done.The document does not address alcohol proof or the labeling of bottles.