If business is now a global affair, then the export-import business is important, lucrative and necessary. An export-import agent is not a broker --- the agents are lower on the business totem pole.
Most properties are measured using a number and a unit of measurement. The unit of measurement is a standard amount. The number compares the property to that standard amount. This means a tree that is ten times as tall as a meter stick is 10 meters tall.
A system of measurement is a collection of units of measurement and rules relating them to each other. Systems of measurement have historically been important, regulated and defined for the purposes of science and commerce. Systems of measurement in modern use include the metric system, the imperial system, and United States customary units.