Quotient of quantities having the same kind-of-quantity in different systems.

Notes:

- The denominator quantity is often called the reference quantity.
- Preferentially the same component is found in the numerator and denominator quantity.

Source:

PAC, 1996, *68*, 957*
(Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations
1996))
* on page 989