AliasNameCategoryTypeinstances are used to organize the AliasNameTypeinstances that a Serverdefines. They can also include instances of AliasNameCategoryTypeto allow hierarchical groupings of AliasNames. It includes a mandatory Methodfor finding instances of AliasNameTypein the AliasName hierarchy, starting at this instance of AliasNameCategoryType. For example, if the Methodcall is made on the Aliases AliasNameCategoryTypeinstance (see 9.2), it would apply the AliasNameSearchPattern to all AliasNamesthat are defined under TagVariables, Topicsand any other AliasNameCategoryTypeinstance in the hierarchy.

The AliasNameCategoryTypeis a subtype of FolderType and is formally defined in Table 2.

Table 2– AliasNameCategoryType Definition

Attribute	Value
BrowseName	AliasNameCategoryType
IsAbstract	False
References	NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the FolderTypefrom OPC 10000-5
Organizes	Object	<Alias>		AliasNameType	OptionalPlaceholder
Organizes	Object	<SubAliasNameCategories>		AliasNameCategoryType	OptionalPlaceholder
HasComponent	Method	FindAlias	Defined in 6.3.2		Mandatory
Conformance Units
AliasName Base

The list of AliasNamesthat an Objectcontains may be dynamic. For example, AliasNamesmay be added in an aggregating Serveras underlying Serversbecome available or may be removed if a Serveris no longer available.

<Alias> represents any number of instances of AliasNameType. Each instance shall have at least one AliasFor Referenceto aNode. Multiple <Alias> instances can point to the same Node.

<SubAliasNameCategories> allows the nesting or structuring of AliasNamesinto hierarchical groupings.

An <Alias> can appear in more than one place in the hierarchy of AliasNameCategories.