Re: Status of RFC 20 (was: Re: Gen-ART and OPS-Dir review of draft-ietf-json-text-sequence-09)

John C Klensin <john-ietf@jck.com> Fri, 19 December 2014 04:48 UTC

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Date: Thu, 18 Dec 2014 23:47:36 -0500
From: John C Klensin <john-ietf@jck.com>
To: Ned Freed <ned.freed@mrochek.com>
Subject: Re: Status of RFC 20 (was: Re: Gen-ART and OPS-Dir review of draft-ietf-json-text-sequence-09)
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Cc: IETF discussion list <ietf@ietf.org>, ned+ietf@mauve.mrochek.com, Julian Reschke <julian.reschke@gmx.de>, John Levine <johnl@taugh.com>, Barry Leiba <barryleiba@computer.org>, Stewart Bryant <stbryant@cisco.com>
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--On Thursday, December 18, 2014 16:05 -0800 Ned Freed
<ned.freed@mrochek.com> wrote:

>> Actually, RFC 20 says, in its very first sentence,
>> "...standard 7-bit ASCII embedded in an 8 bit byte whose high
>> order bit is always 0".   Unless I'm missing something, that
>> is a mapping from a CCS (although ASCII defined those
>> integers in Column/Row form rather than as single integers)
>> and a CES.
> 
> Yep, it's essentially a CES. The only thing missing is the
> definition of the US-ASCII charset name.
> 
>>  So, possibly
>> modulo references to different versions of ASCII (I don't have
>> time to check whether the Charset definition for US-ASCII
>> points to the same version of US-ASCII that RFC 20 does), RFC
>> 20 and US-ASCII are more than just "essentially" the same".
> 
> The CCSs appear identical to me. There may be some subtle
> difference in how some control is defined in the ANSI
> documents versus RFC 20, but that's getting pretty picky.

If one pays attention only to the CCS and ignores character
semantics (as you note, especially for  C0 characters in columns
0 and 1), ASCII is unchanged from the time of its first
publication, i.e., stable both before and after RFC 20.

   john