Nodes in OPC UA have a predefined set of Attributes. They are not extensible by Companion Specifications, only the base specification may add new optional Attributes over time. If there is the need to add more description to a Node, a Property needs to be used. Common Properties are EngineeringUnits or InstrumentRange.

When considering defining a Property, check the set of Attributes defined in the base specification to determine if one of them is suitable. For example, instead of defining a Property called Description, use the corresponding Attribute. OPC UA allows all Attributes to be writable, so even if the requirement is to have a writeable description, the Attribute can be used, and no additional Property should be defined.