This standard Object is the browse entry point for ReferenceType Nodes. Figure 6 illustrates the organization of ReferenceTypes. Organizes References are used to define ReferenceTypes and Objects referenced by the "ReferenceTypes" Object. The "ReferenceTypes" Object shall not reference any other NodeClasses. See Clause 11 for a discussion of the standard ReferenceTypes that appear beneath the "ReferenceTypes" Object.

Figure 6 – ReferenceType definitions

Since ReferenceTypes will be used as filters in the browse Service and in queries, the Server shall provide all its ReferenceTypes, directly or indirectly following hierarchical References starting from the "ReferenceTypes" Object. This means that, whenever the client follows a Reference, the Server shall expose the type of this Reference in the ReferenceType hierarchy. It shall provide all ReferenceTypes so that the client would be able, following the inverse subtype of References, to come to the base References ReferenceType. It does not mean that the Server shall expose the ReferenceTypes that the client has not used any Reference of.

The "ReferenceTypes" Object is formally defined in Table 102.

Table 102 – ReferenceTypes definition

Attribute	Value
BrowseName	ReferenceTypes
References		NodeClass	BrowseName	Comment
HasTypeDefinition		ObjectType	FolderType	Defined in 6.6
Organizes		ReferenceType	References	Defined in 11.1
Conformance Units
Base Info Core Types Folders