Namespaces are used by OPC UA to create unique identifiers across different naming authorities. The Attributes NodeIdand BrowseNameare identifiers. A Nodein the UA AddressSpaceis unambiguously identified using a NodeId. Unlike NodeIds, the BrowseNamecannot be used to unambiguously identify a Node. Different Nodesmay have the same BrowseName. They are used to build a browse path between two Nodesor to define a standard Property.

Serversmay often choose to use the same namespace for the NodeIdand the BrowseName. However, if they want to provide a standard Property, its BrowseNameshall have the namespace of the standards body although the namespace of the NodeIdreflects something else, for example the EngineeringUnits Property. All NodeIdsof Nodesnot defined in this companion specification shall not use the standard namespaces.

Table 87provides a list of mandatory and optional namespaces used in an I4AAS OPC UAServer.

Table 87– Namespaces used in a I4AAS Server

NamespaceURI

Description

Use

http://opcfoundation.org/UA/

Namespace for NodeIdsand BrowseNamesdefined in the OPC UA specification. This namespace shall have namespace index 0.

M

Local Server URI

Namespace for nodes defined in the local server. This may include types and instances used in an AutoID Device represented by the Server. This namespace shall have namespace index 1.

M

http://opcfoundation.org/UA/I4AAS/

Namespace for NodeIdsand BrowseNamesdefined in this companion specification. The namespace index is Serverspecific.

M

Vendor specific types

A Servermay provide vendor-specific types like types derived from ObjectTypes defined in this companion specification in a vendor-specific namespace.

O

Vendor specific instances

A Serverprovides vendor-specific instances of the standard types or vendor-specific instances of vendor-specific types in a vendor-specific namespace.

It is recommended to separate vendor specific types and vendor specific instances into two or more namespaces.

M

Table 88provides a list of namespaces and their index used for BrowseNamesin this companion specification. The default namespace of this companion specification is not listed since all BrowseNameswithout prefix use this default namespace.

Table 88– Namespaces used in this companion specification

NamespaceURI

Namespace Index

Example

http://opcfoundation.org/UA/

0

0:EngineeringUnits

http://opcfoundation.org/UA/Dictionary/URI

2

Admin-shell.io/aas/2/0/1/AssetAdministrationShell