[Editorial Errata Reported] RFC5891 (3969)

[John C Klensin]

(adding Harald, Patrik, Cary, and Paul for reasons that will, I
hope, be obvious)

--On Sunday, 20 April, 2014 10:33 -0400 Barry Leiba
<barryleiba at computer.org> wrote:

>> Section 2.11 of the Unicode Standard explains what combining
>> characters are only in general terms. Section 3.6 contains
>> the actual definition.
> 
> Peter, I see what you're saying, but I don't think a reference
> to Unicode 5.2, Section 3.6, at least not alone, is what was
> meant here in Section 4.2.3.2.  If anything, perhaps this is a
> more appropriate change:
> 
> OLD
>    The Unicode string MUST NOT begin with a combining mark or
> combining    character (see The Unicode Standard, Section 2.11
> [Unicode] for an    exact definition).
> NEW
>    The Unicode string MUST NOT begin with a combining mark or
> combining    character.  See The Unicode Standard, Section
> 2.11 [Unicode] for an    explanation of combining characters,
> and Section 3.6, definition D52 (et    seq) for an exact
> definition.
> END
> 
> John will likely have some memory of what he intended here, so
> let's see what he says.

I'm away from my notes, so this is based on failing memories.  I
might have more to say when I'm closer to them mid-week.  My
recollection is that we wanted to point to what, in Barry's
words above, are the "explanation", rather than the precise
definition, in part because the former is much less
Unicode-version-sensitive than Section 3.6 def D52.   

I have started a 5891bis draft to reflect Barry's suggested
change.

FWIW, with the possible exception of the choice of "exact
definition" rather than "explanation", I don't see this as
properly an erratum.  I believe that Barry's proposed text is an
improvement, but a "hold for future update" improvement not a
correction to a substantive error in the document.   

Barry and Pete, one way of thinking about this as an erratum is
whether, if you received a request in the next several days to
advance IDNA (RFCs 5890-5894 and 6452) to full standard, would
it be blocked on the basis of this comment?  I think the
document is worth a revision to adjust this (and maybe update
the references to 6.x or even 7.0), but others may disagree.

Peter, I can't speak for others, but one of the reasons I
haven't made that request yet is because I haven't done enough
of a recent review of the documents to form an opinion as to
whether a document update is needed to clarify things and, if
so, to which of the documents in the set (possibly including
5984 and 5985).  If you have an opinion on that subject and/or
want to influence mine (or ours), the most efficient way to do
so would be to post a list of proposed changes to the
IDNA-update mailing list so that those who are interested in the
WG's work can review and comment on them.  See below for
information about that list if you haven't found it.

best,
   john

p.s. Why isn't RFC 6452 identified as updating 5892?  It seems
to me that is a real error.


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