Individual measurements (Variables of EnergyMeasurementValueType) have a specific accuracy class defined by a specific accuracy domain. This specification defines accuracy domains in a way, that it is possible to add additional accuracy domains. Each accuracy domain is represented by an Object of AccuracyDomainType (see 7.1.2). The Objects can be browsed from the standardized AccuracyDomains Object (see 10.1), allowing a Client to receive all accuracy domains used by the Server (see Figure 11). This specification defines standardized accuracy domains in 10.

Figure 11 – Accuracy domains

The Object representing an accuracy domain contains the EnumValues Property containing the different accuracy classes defined by the accuracy domain. Each measurement of EnergyMeasurementValueType references its accuracy domain by the Property AccuracyDomain of DataType NodeId. The accuracy class is provided in the AccuracyClass Variable. This Variable of MultiStateValueDiscreteType shall either reference the EnumValues Property of the referenced accuracy domain Object (see VariableA in Figure 12 as example) or it shall contain a copy of that Property containing the same values (see VariableB in Figure 12 as example).

Figure 12 – Usage of accuracy domains and accuracy classes