measurement standard recognized by national authority to serve in a state or economy as the basis for assigning quantity values to other measurement standards for the kind of quantity concerned
ANNOTATION (informative) [2 December 2014] Here "quantity values" can be replaced by "values", and "kind of quantity" can be replaced by "kind", without ambiguity: "measurement standard recognized by national authority to serve in a state or economy as the basis for assigning values to other measurement standards for the kind concerned".