conformance to ECMA-334 or ISO/IEC 23270

Jo Rumpus 25 Reputation points
2026-09-08T23:33:22.7833333+00:00

Does Microsoft’s C# compiler within Visual Studio Community conform to the standards described in ECMA-334 and/or ISO/IEC 23270?

Developer technologies | C#
Developer technologies | C#

An object-oriented and type-safe programming language that has its roots in the C family of languages and includes support for component-oriented programming.

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Tom Tran (WICLOUD CORPORATION) 5,785 Reputation points Microsoft External Staff Moderator
2026-09-09T03:07:33.8166667+00:00

Hi @Jo Rumpus ,

From what I found, Microsoft documents the relationship between Microsoft Visual C# versions and the C# standards on the Ecma TC49-TG2 page. However, I could not find a public Microsoft statement that explicitly declares the C# compiler included with Visual Studio Community formally conformant or certified against ECMA-334 or ISO/IEC 23270.

Also, ISO/IEC 23270:2018 has been withdrawn. The current ISO/IEC publication is ISO/IEC 20619:2023, which references the latest ECMA C# specifications.

The latest published language standard is ECMA-334, 7th edition. Microsoft also explains that the standard currently trails the compiler implementation, so newer C# features are documented separately while the next standard edition is being finalized.

Disclaimer: The Ecma International and ISO pages are third-party standards sources provided for reference.

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  1. Bruce (SqlWork.com) 85,276 Reputation points
    2026-09-10T02:15:52.1633333+00:00

    You have backwards. The EMCA-334 standard follows changes in C#. It’s always behind. As there is only one C# compiler (the mono effort was taken over by Microsoft), it does not need to be certified as it’s the standard.

    Compiler features are based on the GitHub repo that hosts the language specification.

    https://github.com/dotnet/csharplang

    The Roslyn compiler team is responsible for an implementation of the design. The Roslyn compilers are open source.

    https://github.com/dotnet/roslyn

    Also if there is a difference between the compiler implementation and the specification, a team decision will be made to treat as either a compiler bug to fix, or require a change in the specification.

    Note: originally the language design was in the Roslyn repo, but is being moved to its own repo.

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  2. AI answer

    2026-09-08T23:33:33.1333333+00:00

    The provided material confirms that C# itself is standardized through Ecma International and ISO/IEC, and it defines what a conforming C# implementation must do. It does not state whether Microsoft’s C# compiler in Visual Studio Community is certified or declared conformant to ECMA-334 or ISO/IEC 23270.

    Supported facts:

    • The C# Language and the Common Language Infrastructure (CLI) specifications are standardized through Ecma International.
    • The latest official C# standard listed is ECMA-334, 7th edition.
    • ISO/IEC publishes ISO/IEC 23270:2018 for C#.
    • A conforming C# implementation must accept any strictly conforming program and support the required normative parts of the specification.

    References:

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