IDNA Update for Unicode 7.0.0
draft-klensin-idna-5892upd-unicode70-03

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Network Working Group                                         J. Klensin
Internet-Draft
Updates: 5892, 5894 (if approved)                           P. Faltstrom
Intended status: Standards Track                                  Netnod
Expires: July 10, 2015                                   January 6, 2015

                     IDNA Update for Unicode 7.0.0
              draft-klensin-idna-5892upd-unicode70-03.txt

Abstract

   The current version of the IDNA specifications anticipated that each
   new version of Unicode would be reviewed to verify that no changes
   had been introduced that required adjustments to the set of rules
   and, in particular, whether new exceptions or backward compatibility
   adjustments were needed.  That review was conducted for Unicode 7.0.0
   and identified a potentially problematic new code point.  This
   specification discusses that code point and associated issues and
   updates RFC 5892 accordingly.  It also applies an editorial
   clarification that was the subject of an earlier erratum.  In
   addition, the discussion of the specific issue updates RFC 5894.

Status of This Memo

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Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

Klensin & Faltstrom       Expires July 10, 2015                 [Page 1]
Internet-Draft                IDNA-Unicode                  January 2015

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Problem Description . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  IDNA assumptions about Unicode normalization  . . . . . .   5
     2.2.  New code point U+08A1, decomposition, and language
           dependency  . . . . . . . . . . . . . . . . . . . . . . .   6
     2.3.  Other examples of the same behavior . . . . . . . . . . .   7
     2.4.  Hamza and Combining Sequences . . . . . . . . . . . . . .   8
   3.  Proposed/ Alternative Changes to RFC 5892 for new character
       U+08A1  . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     3.1.  Disallow This New Code Point  . . . . . . . . . . . . . .   9
     3.2.  Disallow the combining sequences for these characters . .  10
     3.3.  Do Nothing Other Than Warn  . . . . . . . . . . . . . . .  11
     3.4.  Normalization Form IETF (or DNS)  . . . . . . . . . . . .  11
   4.  Editorial clarification to RFC 5892 . . . . . . . . . . . . .  11
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  13
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  15
   Appendix A.  Change Log . . . . . . . . . . . . . . . . . . . . .  15
     A.1.  Changes from version -00 to -01 . . . . . . . . . . . . .  15
     A.2.  Changes from version -01 to -02 . . . . . . . . . . . . .  15
     A.3.  Changes from version -02 to -03 . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   The current version of the IDNA specifications, known as "IDNA2008"
   [RFC5890], anticipated that each new version of Unicode would be
   reviewed to verify that no changes had been introduced that required
   adjustments to IDNA's rules and, in particular, whether new
   exceptions or backward compatibility adjustments were needed.  When
   that review was carefully conducted for Unicode 7.0.0 [Unicode7],
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