Internationalized Domain Names in Applications (IDNA): Registry Restrictions and Recommendations
draft-klensin-idna-rfc5891bis-04

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Network Working Group                                         J. Klensin
Internet-Draft
Updates: 5890, 5891, 5894 (if approved)                       A. Freytag
Intended status: Standards Track                             ASMUS, Inc.
Expires: February 3, 2020                                 August 2, 2019

    Internationalized Domain Names in Applications (IDNA): Registry
                    Restrictions and Recommendations
                   draft-klensin-idna-rfc5891bis-04

Abstract

   The IDNA specifications for internationalized domain names combine
   rules that determine the labels that are allowed in the DNS without
   violating the protocol itself and an assignment of responsibility,
   consistent with earlier specifications, for determining the labels
   that are allowed in particular zones.  Conformance to IDNA by
   registries and other implementations requires both parts.  Experience
   strongly suggests that the language describing those responsibilities
   was insufficiently clear to promote safe and interoperable use of the
   specifications and that more details and discussion of circumstances
   would have been helpful.  Without making any substantive changes to
   IDNA, this specification updates two of the core IDNA documents (RFC
   5980 and 5891) and the IDNA explanatory document (RFC 5894) to
   provide that guidance and to correct some technical errors in the
   descriptions.

Status of This Memo

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   This Internet-Draft will expire on February 3, 2020.

Klensin & Freytag       Expires February 3, 2020                [Page 1]
Internet-Draft         IDNA: Registry Restrictions           August 2019

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Registry Restrictions in IDNA2008 . . . . . . . . . . . . . .   4
   3.  Progressive Subsets of Allowed Characters . . . . . . . . . .   5
   4.  Considerations for For-Profit Domains . . . . . . . . . . . .   7
   5.  Other corrections and updates . . . . . . . . . . . . . . . .   9
     5.1.  Updates to RFC 5890 . . . . . . . . . . . . . . . . . . .   9
     5.2.  Updates to RFC 5891 . . . . . . . . . . . . . . . . . . .  10
   6.  Related Discussions . . . . . . . . . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  11
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     10.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  15
     A.1.  Changes from version -00 (2017-03-11) to -01  . . . . . .  15
     A.2.  Changes from version -01 (2017-09-12) to -02  . . . . . .  15
     A.3.  Changes from version -02 (2019-07-06) to -03  . . . . . .  15
     A.4.  Changes from version -03 (2019-07-22) to -04  . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  16

1.  Introduction

   Parts of the specifications for Internationalized Domain Names in
   Applications (IDNA) [RFC5890] [RFC5891] [RFC5894] (collectively
   known, along with RFC 5892 [RFC5892], RFC 5893 [RFC5893] and updates
   to them, as "IDNA2008" (or just "IDNA") impose a requirement that
   domain name system (DNS) registries restrict the characters they
   allow in domain name labels (see Section 2 below), and the contents