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) 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. " Jiankang Yao 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