Describes the actual representation of the RepresentedVariables' values. ValueRepresentation is the head of a substitution group which supports a number of representation types, i.e. CodeRepresentation, NumericRepresentation, TextRepresentation, DateTimeRepresentation, ScaleRepresentation, GeographicStructureCodeRepresentation, and GeographicLocationCodeRepresentation. Although the structure allows for specification of missing values these features should be used with caution. Like the definition of the universe and concept, the specification of the representation can be constrained by the Variable (the GSIM ImplementedVariable), for example a NumericRepresentation could be constrained with a lower top coding specification. Missing Values can be assigned separately by the Variable without impact on the ValueRepresentation of the specified valid values provided here.