The Unicode Code Points and Internationalized Domain Names for Applications (IDNA)
RFC 5892

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Internet Engineering Task Force (IETF)                 P. Faltstrom, Ed.
Request for Comments: 5892                                         Cisco
Category: Standards Track                                    August 2010
ISSN: 2070-1721

                      The Unicode Code Points and
         Internationalized Domain Names for Applications (IDNA)

Abstract

   This document specifies rules for deciding whether a code point,
   considered in isolation or in context, is a candidate for inclusion
   in an Internationalized Domain Name (IDN).

   It is part of the specification of Internationalizing Domain Names in
   Applications 2008 (IDNA2008).

Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5892.

Copyright Notice

   Copyright (c) 2010 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
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Faltstrom                    Standards Track                    [Page 1]
RFC 5892                    IDNA Code Points                 August 2010

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Category Definitions Used to Calculate Derived Property
       Value  . . . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  LetterDigits (A) . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  Unstable (B) . . . . . . . . . . . . . . . . . . . . . . .  6
     2.3.  IgnorableProperties (C)  . . . . . . . . . . . . . . . . .  6
     2.4.  IgnorableBlocks (D)  . . . . . . . . . . . . . . . . . . .  7
     2.5.  LDH (E)  . . . . . . . . . . . . . . . . . . . . . . . . .  7
     2.6.  Exceptions (F) . . . . . . . . . . . . . . . . . . . . . .  7
     2.7.  BackwardCompatible (G) . . . . . . . . . . . . . . . . . .  9
     2.8.  JoinControl (H)  . . . . . . . . . . . . . . . . . . . . .  9
     2.9.  OldHangulJamo (I)  . . . . . . . . . . . . . . . . . . . .  9
     2.10. Unassigned (J) . . . . . . . . . . . . . . . . . . . . . .  9
   3.  Calculation of the Derived Property  . . . . . . . . . . . . . 10
   4.  Code Points  . . . . . . . . . . . . . . . . . . . . . . . . . 10
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 11
     5.1.  IDNA-Derived Property Value Registry . . . . . . . . . . . 11
     5.2.  IDNA Context Registry  . . . . . . . . . . . . . . . . . . 11
       5.2.1.  Template for Context Registry  . . . . . . . . . . . . 11
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
   Appendix A.   Contextual Rules Registry  . . . . . . . . . . . . . 13
   Appendix A.1. ZERO WIDTH NON-JOINER  . . . . . . . . . . . . . . . 15
   Appendix A.2. ZERO WIDTH JOINER  . . . . . . . . . . . . . . . . . 16
   Appendix A.3. MIDDLE DOT . . . . . . . . . . . . . . . . . . . . . 16
   Appendix A.4. GREEK LOWER NUMERAL SIGN (KERAIA)  . . . . . . . . . 17
   Appendix A.5. HEBREW PUNCTUATION GERESH  . . . . . . . . . . . . . 17
   Appendix A.6. HEBREW PUNCTUATION GERSHAYIM . . . . . . . . . . . . 18
   Appendix A.7. KATAKANA MIDDLE DOT  . . . . . . . . . . . . . . . . 18
   Appendix A.8. ARABIC-INDIC DIGITS  . . . . . . . . . . . . . . . . 19
   Appendix A.9. EXTENDED ARABIC-INDIC DIGITS . . . . . . . . . . . . 19
   Appendix B.   Code Points 0x0000 - 0x10FFFF  . . . . . . . . . . . 20
   Appendix B.1. Code Points in Unicode Character Database (UCD)
                 Format . . . . . . . . . . . . . . . . . . . . . . . 20
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 69
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 69
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 69

Faltstrom                    Standards Track                    [Page 2]
RFC 5892                    IDNA Code Points                 August 2010

1.  Introduction

   RFC 4690 [RFC4690] suggests an inclusion-based approach for selecting