The Pryonic Metric System is a system of universal measurement developed in Pryonia in the fourth century, calculated on a rational basis from the dimensions of the world and other phenomena. Although a full explanation has not been made publicly available, several realms have adopted the metric system as their principal system of measurement. The base units are believed to be the following:
1 metre: 1/20,000 of the circumference of Telluris.
1 litre: 1/1000 cubic metres
1 gram: weight of 1/1000 litres of water