[Cbor] Status of Appendix A in RFC 8949

Anders Rundgren <anders.rundgren.net@gmail.com> Fri, 05 May 2023 03:37 UTC

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Date: Fri, 05 May 2023 05:37:26 +0200
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From: Anders Rundgren <anders.rundgren.net@gmail.com>
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Subject: [Cbor] Status of Appendix A in RFC 8949
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Hi CBOR WG,

In
https://www.rfc-editor.org/rfc/rfc8949.html#name-examples-of-encoded-cbor-da
there is a table with some example values given in Diagnostic Notation and how they are to be encoded in CBOR.

A problem with this is that the appendix is not marked as "non-normative" although it it is (apparently...) based on Rule 2 in section 4.2.2.

Why is that a problem? Well, in
https://www.ietf.org/archive/id/draft-mcnally-deterministic-cbor-01.html#name-reduction-of-floating-point
Rule 1 is (apparently...) applied, which means that "-4.0" would return 0x23 rather than 0xf9c400 proposed in Appendix A as well as by Carsten's CBOR playground (https://cbor.me/)

Taking CBOR to the world of shrink-wrapped software comparable to Open API will undoubtedly require a CBOR interoperability profile. In such a profile, deterministic encoding is a side effect.

Thanx,
Anders