The IEC standard does not define key words to configure information like the value range or the engineering unit for a Ctrl Variable. The configuration in a programming system is vendor specific but this specification defines the export format in the PLCopen XML Additional Data in the XML element addData.

The InstrumentRange Property defined in OPC 10000-8 shall be provided in the XML element UaInstrumentRange as part of the XML element representing the Ctrl Variable. The attributes of the XML element are formally defined in Table 35.

Table 35 – Range XML attributes

Name	Type	Use	Default
Low	double	required
High	double	required

The EURange Property defined in OPC 10000-8 shall be provided in the XML element UaEURange as part of the XML element representing the Ctrl Variable. The attributes of the XML element are formally defined in Table 35.

The EngineeringUnits Property defined in OPC 10000-8 shall be provided in the XML element UaEngineeringUnits as part of the XML element representing the Ctrl Variable.