Namespaces are used by OPC UA to create unique identifiers across different naming authorities. The NodeId and BrowseName Attributes are identifiers. A Node in the UA Address Space is unambiguously identified using a NodeId. Unlike NodeIds, the BrowseName cannot be used to unambiguously identify a Node. Different Nodes may have the same BrowseName. They are used to build a browse path between two Nodes or to define a standard Property.

Servers may often choose to use the same namespace for the NodeId and the BrowseName. However, if they want to provide a standard Property, its BrowseName shall have the namespace of the standards body although the namespace of the NodeId reflects something else, for example the EngineeringUnits Property. All NodeIds of nodes not defined in this specification shall not use the standard namespaces.

Table 38 provides a list of mandatory and optional namespaces used in an OPC UA Server of a CNC system.

Table 38 – Namespaces used in an OPC UA Server of a CNC system




Namespace for NodeIds and BrowsNames defined in the OPC UA specification. This namespace shall have namespace index 0.


Local Server URI

Namespace for Nodes defined in the local Server. This may include types and instances used in a device represented by the Server. This namespace shall have namespace index 1.


Namespace for NodeIds and BrowsNames defined in this specification. The namespace index is Server specific.


Table 39 provides a list of namespaces and their index used for BrowseNames in this specification. The default namespace of this specification is not listed since all BrowseNames without prefix use this default namespace.

Table 39 – Namespaces used in this specification


Namespace Index