In OPC UA, custom DataTypes have the DataTypeDefinition attribute. This information is also currently missing. It should be checked if it is needed.

Proposal is to specify the usage of the StructureDefinition type in the ATL for structure DataTypes.
The StructureDefinition type has the advantage that the StructureFields are included which deliver the information for ValueRank, MaxStringLength, ArrayDimensions and DataType.
A further advantage of the usage of the StructureDefinition type in the ATL is that this complete StructureDefinition from the ATL can be used for the DataSetMetaData.StructureDataTypes for customized DataSets of a CCS to be created by an FX connection editor.

I have a proposed design for this, but it requires some new rules and conventions. I want to present it in an OE meeting to get agreement before I write it up.

My revised proposal here: https://opcfoundation.sharepoint.com/:u:/r/FLC-WG/Work/@Sub-Groups/Offline_Engineering_WG/Prototyping/AML%20Definition%20Libraries%20Proposal/StructureDefinitionProposal.amlx?csf=1&web=1&e=Nvtz1z
is completely different. No new library is added. Instead, Attributes that should only appear in Types are decorated with the "AdditionalInformation" Header value of "OPCUA:TypeOnly" as shown here:

image.png (55,260 bytes)   

image.png (55,260 bytes)   

So in the RedundantServerDataType example, the four highlighted attributes would be marked as "OPCUA:TypeOnly" so tooling would know to delete them in instances (ideally) or readers would ignore them in instances if not deleted by the tooling.

image-2.png (178,507 bytes)   

image-2.png (178,507 bytes)   

How about using an XML-element instead of separating by column?

"OPCUA:TypeOnly" -> <OPCUA>TypeOnly</OPCUA>

For e.g,, Nodeset2AmlToolVersion it is also done using an XML-element.

Added text to Part 83 draft in A.11.2 to explain the "OPC:TypeOnly" rules.