Re: [Cbor] CBOR magic number, file format and tags Thu, 21 January 2021 03:18 UTC

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To: Doug Ewell <>
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Date: Wed, 20 Jan 2021 22:18:03 -0500
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Subject: Re: [Cbor] CBOR magic number, file format and tags
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"Doug Ewell" <> writes:
>> Since very early in computing, operating systems have sought ways to
>> mark which files could be proposed by which programs.
> The word "proposed" feels very awkward here. Maybe "opened" or
> "manipulated," or some recasting of the sentence that talks about
> files "belonging to" programs, or something similar.

When I first read that, I mis-read it as "processed by".  I suspect that
is what is intended.

But ... Am I missing something?  Isn't a magic number provided by RFC
8949 section 3.4.6?

   3.4.6.  Self-Described CBOR

   Tag number 55799 is defined for this purpose, specifically for use at
   the start of a stored encoded CBOR data item as specified by an
   application.  It does not impart any special semantics on the data
   item that it encloses; that is, the semantics of the tag content
   enclosed in tag number 55799 is exactly identical to the semantics of
   the tag content itself.

   The serialization of this tag's head is 0xd9d9f7, which does not
   appear to be in use as a distinguishing mark for any frequently used
   file types.  [...]