Imperial and US customary measurement systems different concepts – the imperial gallon is defined in terms of the volume occupied by a specified mass of water, while the US gallon is specified in terms of cubic linear measure. Notes Notes Units of weight in both the imperial and US customary system always used the same standard, though differences in multiples of the avoirdupois pound developed in the nineteenth century. Both systems used the three different scales – the avoirdupois system for general use, the troy system for precious metals and the apothecaries system in the pharmacy industry. The term "weight" and "mass" are used interchangeably in
Weight for Age Age Advice U.S. Scale of Weights from about.com Weight for Age Weight for Age (WFA) is a term in Thoroughbred horse racing which is one of the conditions for a race. It means that a horse will carry a set weight in accordance with the Weight for Age Scale. This weight varies depending on the horse’s age, its sex, the race distance and the month of the year. Weight for age races are usually Group 1 races, races of the highest quality. It is a form of handicapping for horse racing, but within the horse racing industry is not referred