Re: [Cbor] Eric Rescorla's Discuss on draft-ietf-cbor-cddl-06: (with DISCUSS and COMMENT)

Carsten Bormann <cabo@tzi.org> Thu, 22 November 2018 01:37 UTC

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From: Carsten Bormann <cabo@tzi.org>
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Date: Thu, 22 Nov 2018 02:36:50 +0100
Cc: Eric Rescorla <ekr@rtfm.com>, cbor@ietf.org, Barry Leiba <barryleiba@computer.org>, IESG <iesg@ietf.org>, draft-ietf-cbor-cddl@ietf.org, cbor-chairs@ietf.org
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To: Benjamin Kaduk <kaduk@mit.edu>
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Subject: Re: [Cbor] Eric Rescorla's Discuss on draft-ietf-cbor-cddl-06: (with DISCUSS and COMMENT)
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On Nov 22, 2018, at 02:24, Benjamin Kaduk <kaduk@mit.edu> wrote:
> 
> […]
> Jumping in on one specific point...
> 
> […]
> I'm still a bit confused on where the #M.N(x) syntax is formally defined.
> Is it supposed to be part of CDDL’s ABNF?

Yes, it is right here in appendix B:

     type2 = [,,,]
           / "#" "6" ["." uint] "(" S type S ")"
           / "#" DIGIT ["." uint]                ; major/ai
           / "#"                                 ; any


(…and quoting the matching rules from appendix C):

         / "#" "6" ["." uint] "(" S type S ")"

   a tagged data item, tagged with the "uint" given and containing the
   type given as the tagged value, or

         / "#" DIGIT ["." uint]                ; major/ai


   a data item of a major type (given by the DIGIT), optionally
   constrained to the additional information given by the uint, or

         / "#"                                 ; any

   any data item.

Grüße, Carsten