Status code BadNodeIdUnknown when reading attributes from a variable in namespaceindex 0 |OPC UA Standard|Forum|OPC Foundation

Hi,

Is it allowed for an OPC UA server to respond status code BadNodeIdUnknown when an OPC UA client reads attributes from a Variable belonging to namespace index 0?
The Variable is in an ObjectType in namespace index 0.

Example:
Assuming an OPC UA client is browsing object type ServerDiagnosticsType (i=2020) and getting a HasComponent reference to Variable SamplingIntervalDiagnosticsArray (i=2022).
When reading the attributes for the Variable the OPC UA server returns BadNodeIdUnknown for all the attributes.

Is this allowed according to the specifications?

Thanks