system of quantities

There are two parallel systems of quantities known as photometric and radiometric quantities.

For this reason, the system of quantities g[f] is said to transform covariantly with respect to changes in the frame f.

Equations in this article are written using the International System of Quantities (ISQ).

The choice of a base system of quantities and units is arbitrary; but once chosen it must be adhered to throughout all analysis which follows for consistency.

A coherent derived unit is defined as a derived unit that, for a given system of quantities and for a chosen set of base units, is a product of powers of base units with no other proportionality factor than one.

The introduction to Part 1 states "The system of quantities, including the relations among the quantities used as the basis of the units of the SI, is named the International System of Quantities, denoted ISQ, in all languages."