Implementation:Onnx Onnx Helper Version Table

Knowledge Sources	ONNX ONNX Versioning
Domains	Versioning, Compatibility
Last Updated	2026-02-10 00:00 GMT

Overview

Concrete tool for querying ONNX version mappings provided by the ONNX helper module.

Description

VERSION_TABLE is a constant data structure in helper.py that maps each ONNX release to its corresponding IR version, ai.onnx opset version, ai.onnx.ml opset version, and (from ONNX 1.7+) ai.onnx.training opset version. The companion find_min_ir_version_for function accepts a list of OperatorSetIdProto objects and returns the minimum IR version required to support all the specified opsets.

Usage

Import VERSION_TABLE when you need to look up version relationships, and find_min_ir_version_for when constructing a model with explicit opset imports to determine the correct IR version.

Code Reference

Source Location

Repository: onnx
File: onnx/helper.py
Lines: 46-78 (VERSION_TABLE), 105-130 (find_min_ir_version_for)

Signature

VERSION_TABLE: list[tuple[str, int, int, int] | tuple[str, int, int, int, int]] = [
    # (release_version, ir_version, ai.onnx_opset, ai.onnx.ml_opset, [ai.onnx.training_opset])
    ("1.0", 3, 1, 1),
    ...
    ("1.20.0", 13, 25, 5, 1),
]

def find_min_ir_version_for(
    opsetidlist: Sequence[OperatorSetIdProto],
    ignore_unknown: bool = False,
) -> int:
    """Given list of opset ids, determine minimum IR version required.

    Args:
        opsetidlist: A sequence of OperatorSetIdProto.
        ignore_unknown: If True, ignore unknown domains and return default.

    Returns:
        The minimum IR version required (integer).
    """

Import

from onnx.helper import VERSION_TABLE, find_min_ir_version_for

I/O Contract

Inputs

Name	Type	Required	Description
VERSION_TABLE	list[tuple]	N/A	Constant: list of (release, ir_ver, onnx_opset, ml_opset, [training_opset])
opsetidlist	Sequence[OperatorSetIdProto]	Yes	List of opset id protos for version lookup
ignore_unknown	bool	No	Ignore unknown domains (default: False)

Outputs

Name	Type	Description
return	int	Minimum IR version required for the given opset imports

Usage Examples

Look Up Version Mapping

from onnx.helper import VERSION_TABLE

# Find the opset version for ONNX 1.16.0
for release, ir_ver, onnx_opset, ml_opset, *rest in VERSION_TABLE:
    if release == "1.16.0":
        print(f"IR: {ir_ver}, ai.onnx opset: {onnx_opset}, ML opset: {ml_opset}")
        # Output: IR: 10, ai.onnx opset: 21, ML opset: 5

Find Minimum IR Version

from onnx.helper import find_min_ir_version_for, make_opsetid

opsets = [make_opsetid("", 17)]
ir_version = find_min_ir_version_for(opsets)
print(f"Minimum IR version for opset 17: {ir_version}")

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