module Const: Owl_const
The SI system of units extends the MKS system and has 7 base units, by expressing any measurement of physical quantities using fundamental units of Length, Mass, Time, Electric Current, Thermodynamic Temperature, Amount of substance and Luminous Intensity, which are Metre, Kilogram, Second, Ampere, Kelvin, Mole and Candela respectively.
http://www.npl.co.uk/upload/pdf/units-of-measurement-poster.pdf
module SI:sig
..end
module Prefix:sig
..end
module MKS:sig
..end
module CGS:sig
..end
module CGSM:sig
..end