 Didot's system was based on Pierre Simon Fournier's (1712–1768), but Didot modified Fournier's by adjusting the base unit precisely to a French Royal inch ("pouce"), as Fournier's unit was based on a less common foot.However, the basic idea of the point system – to generate different type sizes by multiplying a single minimum unit calculated by dividing a base measurement unit such as one French Royal inch – was not Didot's invention, but Fournier's.In Fournier's system, an approximate French Royal inch ("pouce") is divided by 12 to calculate 1 "ligne", which is then divided by 6 to get 1 point.