measurement standard recognized by signatories to an international agreement and intended to serve worldwide
EXAMPLE 1 The international prototype of the kilogram.
EXAMPLE 2 Chorionic gonadotrophin, World Health Organization (WHO) 4th international standard 1999, 75/589, 650 International Units per ampoule.
EXAMPLE 3 VSMOW2 (Vienna Standard Mean Ocean Water) distributed by the International Atomic Energy Agency (IAEA) for differential stable isotope amount-of-substance ratio measurements.