This subtype of the OPC UA FolderTypeis used to structure Nodeslike Properties, Parametersand Methodsaccording to their application (e.g. maintenance, diagnostics, condition monitoring). Organizes Referencesshould be used when the elements are components in other parts of the TopologyElementthat the FunctionalGroupbelongs to. This includes Properties, Variables, and Methodsof the TopologyElementor in Objectsthat are components of theTopologyElementeither directly or via a subcomponent. The same Property, Parameteror Methodmight be useful in different application scenarios and therefore referenced from more than one FunctionalGroup.

FunctionalGroups can be nested.

FunctionalGroupscan directly be instantiated. In this case, the BrowseNameof a FunctionalGroupshould indicate its purpose. A list of recommended BrowseNamesis in 4.4.2.

Figure 3shows the FunctionalGroupTypecomponents. It is formally defined in Table 14.

Figure 3– FunctionalGroupType

Table 14– FunctionalGroupType definition

Attribute	Value
BrowseName	FunctionalGroupType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	Other
Subtype of the 0:FolderTypedefined in OPC 10000-5
0:HasComponent	Object	<GroupIdentifier>		FunctionalGroupType	OP
0:HasComponent	Variable	UIElement	0:BaseDataType	UIElementType	O
Conformance Units
DI Information Model

All BrowseNamesfor Nodesreferenced by a FunctionalGroupwith an Organizes Referenceshall be unique.

The Organizes Referencesmay be present only at the instance, not the type.Depending on the current state of the TopologyElementthe Servermay decide to hide or unhide certain FunctionalGroupsor (part of) their References. If a FunctionalGroupmay be hidden on an instance the TypeDefinitionshall use an appropriate ModellingRulelike “Optional”.

If desirable, Nodescan be also children of FunctionalGroups. If such Nodesare defined, it is recommended to define a subtype of the FunctionalGroupType.

UIElementis the user interface element for this FunctionalGroup. See 4.4.3for the definition of UIElements.

Examples in Annex B.1illustrate the use of FunctionalGroups.

Table 15includes a list of FunctionalGroupswith name and purpose. If Serversexpose a FunctionalGroupthat corresponds to the described purpose, they should use the recommended BrowseNamewith the Namespace of this specification.

Table 15– Recommended FunctionalGroup BrowseNames

BrowseName	Purpose
Configuration	Parametersrepresenting the configuration items of the TopologyElement. If the CurrentWritebit is set in the AccessLevel Attributethey can be modified by Clients.
Tuning	Parametersand Methodsto optimize the behavior of the TopologyElement.
Maintenance	Parametersand Methodsuseful for maintenance operations.
Diagnostics	Parametersand Methodsfor diagnostics.
Statistics	Parametersand Methodsfor statistics.
Status	Parameterswhich describe the general health of the TopologyElement. This can include diagnostic Parameters.
Operational	Parametersand Methodsuseful for during normal operation, like process data.
OperationCounters	Parametersrepresenting numbers of interest when managing a TopologyElementwhile it is operated. Examples are the hours of operation, hours in standby, etc. Those are often the base to calculate KPIs (key performance indicators) like the OEE (overall equipment efficiency). Parametersare often domain specific. Some common ones are defined in the OperationCounter Interface (see 4.5.5).This FunctionalGroupmight be organized into other FunctionalGroups, so Clientsshall expect that they need to browse several hops to get to allOperationCounters.
Identification	ThePropertiesof the VendorNameplate Interface, like Manufacturer, SerialNumber or Propertiesof the TagNameplate will usually be sufficient as identification. If other Parametersor even Methodsare required, all elements needed shall be organized in a FunctionalGroupcalled Identification. See Annex B.1for an example.

Servers can expose UIElementsproviding user interfaces in the context of their FunctionalGroupcontainer. Clients can load such a user interface and display it on the Clientside. The hierarchy of FunctionalGroupsrepresents the tree of user interface elements.

The UIElementTypeis abstract and is mainly used as filter when browsing a FunctionalGroup. Only subtypes can be used for instances. No concrete UIElementsare defined in this specification. FDI (Field Device Integration, see IEC 62769) specifies two concrete subtypes

• UIDs (UI Descriptions), descriptive user interface elements, and
• UIPs (UI Plug-Ins), programmed user interface elements.

The UIElementTypeis specified in Table 16.

Table 16– UIElementType definition

Attribute	Value
BrowseName	UIElementType
IsAbstract	True
DataType	0:BaseDataType
References	NodeClass	BrowseName	DataType	TypeDefinition	Other
Subtype of the 0:BaseDataVariableTypedefined in OPC 10000-5.
Conformance Units
DI Information Model

The Valueattribute of the UIElementcontains the user interface element. Subtypes have to define the DataType(e.g., XmlElementor ByteString).