Mapping of model metadata between ONNX format and Ort::ModelMetadata?

[lukasberbuer]

The ONNX protobuf format specifies model properties ModelProto and onnxruntime exposes the struct Ort::ModelMetadata.

The mapping from ONNX to Ort seems to be following:

• ir_version -> ?
• opset_import -> ?
• producer_name -> Ort::ModelMetadata::GetProducerName()
• producer_version -> ?
• domain -> Ort::ModelMetadata::GetDomain()
• model_version -> Ort::ModelMetadata::Version()
• graph.name -> Ort::ModelMetadata::GetGraphName()
• graph.doc_string -> Ort::ModelMetadata::GetGraphDescription()
• doc_string -> Ort::ModelMetadata::GetDescription()
• metadata_props -> Ort::ModelMetadata::GetCustomMetadataMapKeys() / Ort::ModelMetadata::LookupCustomMetadataMap()

Why are not all properties available via onnxruntime? Is it possible to retrieve e.g. ir_version anyway?