Internationalized Domain Names Registration and Administration Guidelines for European Languages Using Cyrillic
RFC 5992

Document Type RFC - Informational (October 2010; No errata)
Last updated 2015-10-14
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Independent Submission                                       S. Sharikov
Request for Comments: 5992                                   Regtime Ltd
Category: Informational                                    D. Miloshevic
ISSN: 2070-1721                                                  Afilias
                                                              J. Klensin
                                                            October 2010

     Internationalized Domain Names Registration and Administration
            Guidelines for European Languages Using Cyrillic

Abstract

   This document is a guideline for registries and registrars on
   registering internationalized domain names (IDNs) based on (in
   alphabetical order) Bosnian, Bulgarian, Byelorussian, Kildin Sami,
   Macedonian, Montenegrin, Russian, Serbian, and Ukrainian languages in
   a DNS zone.  It describes appropriate characters for registration and
   variant considerations for characters from Greek and Latin scripts
   with similar appearances and/or derivations.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see 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/rfc5992.

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
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Sharikov, et al.              Informational                     [Page 1]
RFC 5992                      Cyrillic IDNs                 October 2010

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
     1.1.  Similar Characters and Variants  . . . . . . . . . . . . .  3
     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Languages and Characters . . . . . . . . . . . . . . . . . . .  5
     2.1.  Bosnian and Serbian  . . . . . . . . . . . . . . . . . . .  5
     2.2.  Bulgarian  . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.3.  Byelorussian (Belarusian, Belarusan) . . . . . . . . . . .  5
     2.4.  Kildin Sami  . . . . . . . . . . . . . . . . . . . . . . .  6
     2.5.  Macedonian . . . . . . . . . . . . . . . . . . . . . . . .  7
     2.6.  Montenegrin  . . . . . . . . . . . . . . . . . . . . . . .  7
     2.7.  Russian  . . . . . . . . . . . . . . . . . . . . . . . . .  7
     2.8.  Serbian  . . . . . . . . . . . . . . . . . . . . . . . . .  7
     2.9.  Ukrainian  . . . . . . . . . . . . . . . . . . . . . . . .  8
   3.  Language-Based Tables  . . . . . . . . . . . . . . . . . . . .  8
   4.  Table Processing Rules . . . . . . . . . . . . . . . . . . . .  8
   5.  Table Format . . . . . . . . . . . . . . . . . . . . . . . . .  8
   6.  Steps after Registering an Input Label . . . . . . . . . . . .  9
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 10
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     9.2.  Informative References . . . . . . . . . . . . . . . . . . 10
   Appendix A.  European Cyrillic Character Tables  . . . . . . . . . 13

1.  Introduction

   Cyrillic is one of a fairly small number of scripts that are used,
   with different subsets of characters, to write a large number of
   languages, some of which are not closely related to the others.  When
   those languages might be used together in a zone (typical of generic
   TLDs (gTLDs) but likely in other zones both at and below the root),
   special considerations for intermixing characters may apply.
   Cyrillic also has the property that, while it is usually considered a
   separate script from the Latin (Roman) and Greek ones, it shares many
   characters with them, creating opportunities for visual confusion.
   Those difficulties are especially pronounced when "all of Cyrillic"
   is used rather than only the characters associated with a particular
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