"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) 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), followed by a string that is a valid output
      of the Punycode algorithm [RFC3492] and hence a maximum of 59
      ASCII characters in length. "

From: Don Hollander

Date: 2017-01-22 17:33

To: ua-eai@icann.org

CC: Tan Tanaka, Dennis; Mark Svancarek via UA-Coordination; Dr. AJAY D A T A; Stuart Stuple

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