For mapping an IODD Record datatype to an OPC UA DataType as subtype of Structure the IODD Record@id is required to generate the NodeId, but in the IODD the id for a data type is only present when the datatype appears inside the DatatypeCollection, otherwise it shall not be present. So the NodeId cannot be created, if the id is not present.

The IO-Link for OPC UA companion specification defines that an IODD Record type must have an id to create the NodeId for the new DataType:

12.3.2 Structure DataType
For each IODD Record a new OPC UA DataType as subtype of Structure is created.
• The NodeId of the new DataType is composed of the NodeId of the ObjectType generated for the IODD (see section 7.3.2) and the Record/@id (“<ObjectTypeId>||<Record id>”).

The IODD specification defines that the id for a data type is only present if the type is defined inside the DatatypeCollection, otherwise it shall not be present:

7.5.2 Data type collection
[snip]
id (c, IdT)
Datatype elements within the DatatypeCollection shall have an attribute ‘id’. Datatype elements outside of the DatatypeCollection shall not have an attribute ‘id’.

7.5.3.1.1 General

When the Datatype element appears inside the DatatypeCollection, the attribute ‘id’ shall be present. Otherwise, the attribute ‘id’ shall not be present.

So if the type is defined inside a Variable declaration or inside a ProcessData declaration it has no id. So the NodeId for the new OPC UA DataType cannot be created.