Systeme International d'Unites
From The Glossary of Digital Photography
Also known as SI system. An international measuring system based on the original metric system. The SI system has seven base units: length (meter), mass (kilogram), time (second), electrical current (ampere), temperature (kelvin), amount of substance (mole), and luminous intensity (candela). Prefixes are added to define a smaller or larger amount of the original unit; these include kilo, mega, and giga for larger, and centi, milli, and micro for smaller.
