[UA-EAI] [UA-Coordination] Revised UASG013 - Quick Guide to EAI

[Mark Svancarek]

Good catch.  The ACE prefix indicates to a parser that the following string is the Punycoded transformation of an IDNA-compatible Unicode string, but is not actually a part of that transformation.

From: ua-eai-bounces at icann.org [mailto:ua-eai-bounces at icann.org] On Behalf Of Jiankang Yao
Sent: Sunday, January 22, 2017 6:27 PM
To: Don Hollander <don.hollander at icann.org>; ua-eai at icann.org
Cc: ua-coordination at icann.org
Subject: Re: [UA-EAI] [UA-Coordination] Revised UASG013 - Quick Guide to EAI

Hello,

  The definition
"Punycode is an algorithm that converts an IDN into an ASCII string that starts with xn--. The Punycode
algorithm is bi-directional. " needs some adjustment.


xn--abcdeddaa
where  "xn--" is a prefix and "abcdeddaa" is  output of the Punycode algorithm. So Punycode output does not include "xn--".




======================================following are texts from RFC5890===============================
" the string following "xn--" must be the valid output of the Punycode algorithm
                    and must be convertible into valid U-label form."

"An "A-label" is the ASCII-Compatible Encoding (ACE, see
      Section 2.3.2.5<https://tools.ietf.org/html/rfc5890#section-2.3.2.5>) form of an IDNA-valid string.  It must be a
      complete label: IDNA is defined for labels, not for parts of them
      and not for complete domain names.  This means, by definition,
      that every A-label will begin with the IDNA ACE prefix, "xn--"
      (see Section 2.3.2.5<https://tools.ietf.org/html/rfc5890#section-2.3.2.5>), followed by a string that is a valid output
      of the Punycode algorithm [RFC3492<https://tools.ietf.org/html/rfc3492>] and hence a maximum of 59
      ASCII characters in length. "

________________________________
Jiankang Yao

From: Don Hollander<mailto:don.hollander at icann.org>
Date: 2017-01-22 17:33
To: ua-eai at icann.org<mailto:ua-eai at icann.org>
CC: Tan Tanaka, Dennis<mailto:dtantanaka at verisign.com>; Mark Svancarek via UA-Coordination<mailto:ua-coordination at icann.org>; Dr. AJAY D A T A<mailto:ajay at data.in>; Stuart Stuple<mailto:stuartst at exchange.microsoft.com>
Subject: [UA-Coordination] Revised UASG013 - Quick Guide to EAI
Last month I sent out a formatted Quick Guide to EAI.

This resulted in a number of comments from Ajay, Stuart, Mark, Lars & Dennis.

These enhancements were mostly focused on the Email Service Provider.

I have revised the source document which is attached.

And for reference, I’m also including the formatted earlier draft.

Could I please get any final comments by the end of this week (25th)?

Thanks.

Don
















Don Hollander
Universal Acceptance Steering Group
Skype: don_hollander




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