The section defines common variable types that are used by multiple section of the ISA specification (i.e. equipment and physical assets etc.) In some cases these types define a generic version of the variable that will be further customized in the specific section, i.e. equipment or physical asset variable section.

The variable types defined in the following sections make use of reference types that are defined in section 9. These reference types provide specific semantic information. To fully understand the Variable or Object models it may be required to review these reference descriptions.

The ISA95ClassPropertyType is an abstract VariableType that cannot be used directly. It must be subtyped to be used. It is a subtype of BaseDataVariableType defined in OPC 10000-5.

This VariableType is used to define an ISA95ClassProperty for an ISA95Class.

Table 42 – ISA95ClassPropertyType definition

Attribute	Value
BrowseName	ISA95ClassPropertyType
IsAbstract	True
ValueRank	0 (OneOrMoreDimensions)
DataType	BaseDataType
References		NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the BaseDataVariableType defined in OPC 10000-5
HasISA95Attribute		Variable	Key	CDTIdentifier	BaseDataVariableType	Optional

The Key defines an Id to differentiate between the different values. When multiple values are stored to the Value attribute this ISA95Attribute is used. For example a value may be a series of numbers, such as a series of peak values from a spectrometer.

The ISA95PropertyType is an abstract VariableType that cannot be used directly. It must be subtyped to be used. It is a subtype of BaseDataVariableType defined in OPC 10000-5.

This VariableType is used to define an ISA95Property for an ISA95Object.

Table 43 – ISA95PropertyType definition

Attribute	Value
BrowseName	ISA95PropertyType
IsAbstract	True
ValueRank	0 (OneOrMoreDimensions)
DataType	BaseDataType
References		NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the BaseDataVariableType defined in OPC 10000-5
HasISA95Attribute		Variable	Key	CDTIdentifier	BaseDataVariableType	Optional

Key defines an Id to differentiate between the different values. When multiple values are stored to Value attribute this ISA95Attribute is used. For example a value may be a series of numbers, such as a series of peak values from spectrometer.

The ISA95TestResultdType is a concrete VariableType that can be used directly. It is a subtype of BaseDataVariableType defined in OPC 10000-5.

This VariableType indicates the test results. Value attribute of this DataVariable is structured data. However, each element of the structure can be accessed via Properties.

Table 44 – ISA95TestResultType definition

Attribute	Value
BrowseName	ISA95TestResultType
IsAbstract	False
ValueRank	0 (OneOrMoreDimensions)
DataType	Structure
Historizing	True
References		NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the BaseDataVariableType defined in OPC 10000-5
HasISA95Attribute		Variable	Id	NodeId	PropertyType	Mandatory
HasISA95Attribute		Variable	ResultDescription	LocalizedText	PropertyType	Mandatory
HasISA95Attribute		Variable	TestDate	DateTime	PropertyType	Mandatory
HasISA95Attribute		Variable	Result	BaseDataType	PropertyType	Mandatory
HasISA95Attribute		Variable	ResultUnitOfMeasure	BaseDataType	PropertyType	Mandatory
HasISA95Attribute		Variable	Expiration	DateTime	PropertyType	Mandatory

Note: The Variable has a DataType of Structure which is generic and must be assigned to a defined sub-type before it is transmitted on the wire. The generic Structure DataType results in an ExtensionObject being placed on the wire. The default defined sub-type is either ISA95TestResultDataType or ISA95TestResultMeasurementDataType depending on the nature of the data. If a different structure is used, it shall include all of the fields defined in this structure and the defined sub-type of this variable type shall also include any additional fields that are in the structure as separate variables.

Id is an identifier of the Test Result. This field can be used to reference the actual result.

ResultDescription is an additional information or description of the test result.

TestDate is the date and time of the test. This Time is used to determine when a test expires, it is server specific as to whether it is a test start time or end time, but it should be consistent in all cases.

Result is the result of the test (further defined in subtypes).

ResultUnitOfMeasure is the unit of measure of the associated test result. It is defined as a structure to allow either a EUInformation or a measurement code (clause 6.3.8) to be reported.

Expiration is the date of the expiration of the test result.