Subject: Re: [weirds] search for A-labels

From: "John R Levine" <[email-masked]>
Date: 23 Jul 2013 16:12:54 -0400

> The point Scott is trying to make, I think, is that we are attempting to
> define how two pieces of software interoperate and that unpredictable
> results are likely in this case. At the very least we should point out
> that the results will be unpredictable or at-best based on partial match
> semantics of ASCII only.

Hmmn.  If you look for ab* you can't tell whether that's an ASCII pattern or a 
U-label pattern.  If you look for xn--ab* it's definitely an A-label pattern.

Regards,
John Levine, [email-masked], Primary Perpetrator of "The Internet for Dummies",
Please consider the environment before reading this e-mail. http://jl.ly

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From: Andy Newton <[email-masked]>
Date: Wed, 24 Jul 2013 10:06:36 +0000

On 7/23/13 4:12 PM, "John R. Levine" <[email-masked]> wrote:

>Hmmn.  If you look for ab* you can't tell whether that's an ASCII pattern
>or a U-label pattern.  If you look for xn--ab* it's definitely an A-label
>pattern.

Yes, that's right. I believe that is why we received the advice about ab*
being a search for all the combinations that 'b' could be combined with if
it were a Unicode character that might be combined with another Unicode
character and the references to the docs specifying the list of
combinations.

FWI, I don't have a strong opinion on this either way. I just know that
I18N search is non-trivial and I doubt we'll get to publication in the
IETF if we don't have a good answer for it.

-andy