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All targets of forward hierarchical References from a TypeDefinitionNode shall have a BrowseName that is unique within the TypeDefinitionNode. The same restriction applies to the targets of forward hierarchical References from any InstanceDeclaration. This means that any InstanceDeclaration within the InstanceDeclarationHierarchy can be uniquely identified by a sequence of BrowseNames. This sequence of BrowseNames is called a BrowsePath.