Re: [precis] Ambiguity in specification of case mapping in RFC 7613 and draft-ietf-precis-nickname

Peter Saint-Andre <> Tue, 27 October 2015 13:52 UTC

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To: Peter Saint-Andre - &yet <>, John C Klensin <>, Tom Worster <>, Alexey Melnikov <>
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From: Peter Saint-Andre <>
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Date: Tue, 27 Oct 2015 07:52:20 -0600
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Subject: Re: [precis] Ambiguity in specification of case mapping in RFC 7613 and draft-ietf-precis-nickname
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This issue has greater urgency now because draft-ietf-precis-nickname is 
now in AUTH48...

On 10/26/15 3:51 PM, Peter Saint-Andre - &yet wrote:

> After all that, I have 3 questions:
> (1) Is my proposed text enough of a clarification that we should make
> that change before the nickname I-D is published as an RFC?

I think so.

> (2) Should we modify draft-ietf-precis-nickname so that case folding is
> applied only as part of comparison and not as part of enforcement? If
> so, should we make that change before this document is published as an RFC?

Although it seems to be the case that Unicode case folding is primarily 
designed for the purpose of matching (i.e., comparison), I have a 
concern that applying the PRECIS case mapping rule after applying the 
normalization and directionality rules might have unintended 
consequences that we haven't had a chance to consider yet. The PRECIS 
framework expresses a preference (actually a hard requirement) for 
applying the rules in a particular order. We made a late change to the 
username profiles (RFC 7613), such that width mapping is applied first 
(in order to accommodate fullwidth and halfwidth characters in certain 
East Asian scripts). Making a late change to the nickname profile also 
concerns me, even though both of these late changes seem reasonable on 
the face of it. I will try to find time to think about this further in 
the next 24 hours.

> (3) Should we update RFC 7613 so that case folding is applied only as
> part of comparison and not as part of enforcement?

That is less urgent so I suggest that we address the nickname spec first.