Identifier at the source system for the described-value-domain. Used during import to determine if the entity already exists in the target system (update) or is new (create). Must remain stable in the source system for the same entity. The designation of the described-value-domain Explanation of the described-value-domain Level of measurement (nominal, ordinal, interval, or ratio) indicating what statistical operations are valid on the data values. Based on Stevens' measurement theory, this determines allowed computations: nominal data supports only counting and mode; ordinal adds median and ranking; interval adds arithmetic operations (but not ratios); ratio supports all arithmetic operations including meaningful ratios. Reference to DescribedConceptualDomain (instantiates concept) Reference to MeasurementType (measured using type)