Re: [Cbor] tags for non-CBOR Content-Formats (was Re: I-D Action: draft-ietf-cbor-file-magic-07.txt)

Michael Richardson <mcr+ietf@sandelman.ca> Thu, 16 December 2021 01:46 UTC

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From: Michael Richardson <mcr+ietf@sandelman.ca>
To: Carsten Bormann <cabo@tzi.org>, cbor@ietf.org
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Date: Wed, 15 Dec 2021 20:46:34 -0500
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Subject: Re: [Cbor] tags for non-CBOR Content-Formats (was Re: I-D Action: draft-ietf-cbor-file-magic-07.txt)
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Carsten Bormann <cabo@tzi.org> wrote:
    >> This is in: https://datatracker.ietf.org/doc/html/draft-ietf-cbor-file-magic-07.txt#appendix-C
    >> I see the argument to make this an appendix since it does not tag CBOR
    >> content.  I fear that the reviewers and IESG will be confused though.

    > We could add more text why this is in an appendix.

I guess so.

    >>
    >> Should it really use CBOR as bytes 8-11, since the content is not, in fact, CBOR?

    > The header is.

Yeah, but for the human who saw this in the hexdump-C, if they get their CBOR
decoder out, they will be slightly annoyed once they realize that it is only
the header.
Is there another four letter word that starts with C?
(no, not that one)

%grep -i '^c[a-z][a-z][a-z]$' /usr/share/dict/words | wc -l
186

"cite" is one.... coax. coat. cork. crop.... czar.
I have no reason to pick these, but the prefix is kinda of a coat.
It could also be "CONT"ains.

    >> Maybe we should say something else.  I don't feel strongly about this.

    > I thought about that, but the tag should be the determining factor;
    > keeping the information in two places invites mismatches.

I take your point.
My point is that those bytes were because we had to wrap something, and it
provided a nice clue to the human who sees them.
Again, I don't feel strongly.







--
Michael Richardson <mcr+IETF@sandelman.ca>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide