Subject: [idn] Case-insensitiveness of prefix

From: YangWoo Ko <[email-masked]>
Date: Sun, 11 Nov 2001 22:30:48 +0900

According to Section 5. of last IDNA document (draft-ietf-idn-idna-04.txt),
"It(=prefix) MUST be recognized in a case-insensitive manner."

I could not understand implications of that statement. Does it mean that
IDNA prohibit the use of case information of prefix for any purpose ?

For example, case information of prefix may be utilized as a parity check
for any purpose.

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From: [email-masked] <[email-masked]>
Date: Sun, 11 Nov 2001 23:29:21 +0800

----- Original Message -----
From: "YangWoo Ko" <[email-masked]>
To: <[email-masked]>
Sent: Sunday, November 11, 2001 9:30 PM
Subject: [idn] Case-insensitiveness of prefix

> "It(=prefix) MUST be recognized in a case-insensitive manner."

    " recognized " means the answer. That is say: { BQ--, bq--, Bq--, bQ-- }
are recognized as the same . There are no over-specification that MUST  be
forced these case to converted to lower case.

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From: David Hopwood <[email-masked]>
Date: Sun, 11 Nov 2001 13:04:46 +0000

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> IDNA prohibit the use of case information of prefix for any purpose ?

It means that labels where the prefix characters differ in case are
equivalent. (That should be true for any proposal that uses ACE, not
just IDNA.)

> For example, case information of prefix may be utilized as a parity check

No, it couldn't reliably be used as a parity check, because the case of
an ACE label may be changed.

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David Hopwood <[email-masked]>

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From: "Adam M. Costello" <[email-masked]>
Date: Mon, 12 Nov 2001 02:02:50 +0000

> I could not understand implications of that statement.

Here's what I meant when I wrote it:  Step 5 of ToASCII and step 3 of
ToUnicode (which check for the presence or absence of the ACE prefix)
must disregard the case of the letters in the ACE prefix.

> Does it mean that IDNA prohibit the use of case information of prefix
> for any purpose?

That was not my intention.  Perhaps the statement should be clarified.
Paul, how about changing that sentence to:

    The ToASCII and ToUnicode operations MUST recognize the ACE prefix
    in a case-insensitive manner.

AMC