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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.
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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
language.
This specification provides guidelines for the use of Cyrillic, as
encoded in Unicode [Unicode52] with internationalized domain name
(IDN) labels derived from most "European" languages that use the
script (use of the term "European" is a convenience, since there is
disagreement about the relevant boundaries for different purposes
and, of course, much of Russia lies within geological Asia).
Specifically, it covers (in alphabetic order) Bosnian, Bulgarian,
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Byelorussian, the Kildin member of the Sami (often written "Saami")
language family, Macedonian, Montenegrin, Russian, Serbian, and
Ukrainian. Supplemental tables, based on information in the Unicode
Standard and a recently completed Montenegrin government standard
[MontenegrinChars] are provided for use with Montenegrin. Moldovan
is no longer in official use with Cyrillic script: no registrations
are considered likely in Cyrillic, at least within the relevant
ccTLD, and it is not further discussed in this document. Languages
of Asia that use Cyrillic are not considered here and should be the
subject of separate specifications.
While Cyrillic script is the primary one used for many of the
relevant languages and countries, Latin script is often used instead
of, or in combination with, it. Standard keyboards used in most of
the countries have both Cyrillic and Latin characters. Therefore,
some registries could use Latin scripts for domain name registration
in their zones. From time to time, some registries and users have
claimed that there is a requirement for mixing Cyrillic and Latin
characters in the same label. We strongly recommend against such
mixing as user confusion is almost certain to result. In addition,
registries that support many scripts will probably encounter the need
to support labels in Greek or Latin scripts as well as Cyrillic, and
a large number of character forms are shared among those three
scripts.
Because the DNS has no way for the end user to distinguish among the
languages that might have been used to inspire a particular label, it
seems useful to treat the characters of a large number of languages
that use Cyrillic in their writing systems together, rather than
trying to differentiate them. The discussion and tables in this
specification should provide a foundation for developing more
restrictive rules for zones in which only a single language is likely
to be used, but it does not specify those language-specific rules.
Readers of this document should be aware that its recommendations are
about use in DNS labels. The orthography for some of the languages
involved, especially Kildin Sami, is not completely standardized and
local usage sometimes permits substitution of Latin-based characters
for their Cyrillic equivalents. Unless they are required by official
orthographies, those substitutions should generally be avoided in DNS
labels because of the risk of additional user confusion with the
Latin characters that are visually similar.
1.1. Similar Characters and Variants
For some human languages, there are characters and/or strings that
have equivalent or near-equivalent meanings. If someone is allowed
to register a name with such a character or string, the registry
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might want to automatically register all the names that have the same
meaning in that language. Further, some registries might want to
restrict the set of characters to be registered for language-based
reasons.
So-called "variant techniques", introduced in the JET specification
for the CJK script [RFC3743] and its generalization [RFC4290],
describe ways of registering IDNs to decrease the risk of
misunderstandings, cybersquatting, and other forms of confusion.
The tables below (Appendix A) identify confusable characters in Latin
and Greek scripts that might be easily confused with Cyrillic ones.
As with variant approaches for other scripts (e.g., see RFC 4713
[RFC4713] for the Chinese language or RFC 5564 [RFC5564] for the
Arabic language), this document identifies sets of characters that
need special consideration and provides information about them. A
registry that handles names using these characters can then make a
policy decision about how to actually handle them. The options for
those policy decisions would include automatically registering all
look-alike strings to the same registrant, registering one such
string and blocking the others, and so on.
1.2. Terminology
The terminology that follows is derived from the JET specification
for the CJK script [RFC3743] and its generalization [RFC4290], but
this specification does not depend on them. All characters listed
here have been verified to be "PVALID" under the IDNA2008
specification [RFC5890] [RFC5892].
A "string" is a sequence of one or more characters.
This document discusses characters that have equivalent or near-
equivalent characters or strings. The "base character" is the
character that has one or more equivalents; the "variant(s)" are the
character(s) and/or string(s) that are equivalent to the base
character.
A "registration bundle" is the set of all labels that comes from
expanding all base characters for a single name into their variants.
A registry is the administrative authority for a DNS zone. That is,
the registry is the body that makes and enforces policies that are
used in a particular zone in the DNS. The term "registry" applies to
all zones in the DNS, not only those that exist at the top level.
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2. Languages and Characters
In the interest of clarity and balance, this document describes a
"Base Cyrillic" set of 23 characters for use in comparing the
character usage for Russian and Central European languages that use
Cyrillic. The balance of this section compares the character usage
of the individual languages in that group.
"Base Cyrillic" consists of the following Unicode code points (names
associated with these code points and those below appear in
Appendix A): U+0430, U+0431, U+0432, U+0433, U+0434, U+0435, U+0436,
U+0437, U+043A, U+043B, U+043C, U+043D, U+043E, U+043F, U+0440,
U+0441, U+0442, U+0443, U+0444, U+0445, U+0446, U+0447, U+0448.
In addition, modern writing systems that use Cyrillic do not have
digits separate from the "European" ones used with Latin characters.
For registries that permit digits to appear in domain name labels,
the "Base Cyrillic" code point listed above should be considered to
include U+0030, U+0031, U+0032, U+0033, U+0034, U+0035, U+0036,
U+0037, U+0038, and U+0039 (Digit Zero, and Digit One through Digit
Nine). The Hyphen-Minus character (U+002D) may also be used.
It is worth noting that the EU top-level domain registry allows
Cyrillic registrations using 32 code points [EU-registry]. That list
is sufficient for some of the languages listed here but not for
others.
The individual languages that are the focus of this specification are
discussed below (in English alphabetical order).
2.1. Bosnian and Serbian
Bosnian and Serbian have 30 letters in the alphabet and the
additional seven characters to the base of 23 shared Cyrillic
characters: U+0438, U+0458, U+0452, U+0459, U+045A, U+045B, U+045F.
2.2. Bulgarian
The Bulgarian alphabet has 30 characters, seven in addition to the
basic 23: U+0438, U+0439, U+0449, U+044A, U+044C, U+044E, U+044F.
2.3. Byelorussian (Belarusian, Belarusan)
The Byelorussian (now often spelled Belarusian or Belarusan) alphabet
has 32 characters, i.e., nine characters in addition to the Base
Cyrillic set of 23 characters: U+0451, U+0456, U+0439, U+044B,
U+044C, U+045E, U+044D, U+044E, U+044F.
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2.4. Kildin Sami
The phonetics of the Kildin Sami are quite complex and not easily
represented in Cyrillic (see, e.g., Kertom's work [Kert]). The
orthography is not standardized and the writing system may best be
thought of as an attempt to transcribe the language phonetically
(primary in Latin script in the 1930s but in Cyrillic more recently).
Different scholars have reported different numbers of phonemes,
further complicating the transcription process. Kertom identifies 53
consonants with long-short distinctions and, in many cases, hard-soft
ones. He also identifies ascending and descending diphthongs and one
triphthong as well as more common short and long vowels.
The primary reference for Kildin Sami, widely circulated for some
time but only in draft, is apparently used by Sami language(s)
experts in Scandinavian countries [Riessl07]. It, and the references
it cites, uses 56 characters, 33 of which do not appear in the basic
set. Eight* of these characters have no precomposed forms in Unicode
and hence must be written as a sequence of two code points with the
second one being COMBINING MACRON (U+0304). Using parentheses to
make the two-code-point sequences more obvious, the additional
characters are: (U+0430 U+0304)*, (U+0435 U+0304)*, U+0438, U+0439,
(U+043E U+0304), U+044A, U+044B, (U+044B U+0304), U+044C, U+044D,
(U+044D U+0304), U+044E, (U+044E U+0304), U+044F, (U+044F U+0304),
U+0451, (U+0451 U+0304), U+0458, U+048B, U+048D, U+048F, U+04BB,
U+04C6, U+04C8, U+04CA, U+04CE, U+04D3, U+04E3, U+04E7, U+04ED,
U+04EF, U+04F1, U+04F9.
* These characters, CYRILLIC SMALL LETTER A (U+0430) with a
COMBINING MACRON (U+0304) and CYRILLIC SMALL LETTER IE (U+0435)
with a COMBINING MACRON (U+0304), respectively, have the same
visual appearance as LATIN SMALL LETTER A WITH MACRON (U+0101) and
LATIN SMALL LETTER E WITH MACRON (U+0113). There are no known
keyboards designed specifically for Kildin Sami. If an extended
Latin-based keyboard and associated software are used, these
characters might appear with the code point based on Latin (e.g.,
U+0113 for the second case). By contrast, keyboards and input
software that are designed to be more Cyrillic-friendly are more
likely to produce code points for the Cyrillic base characters.
The use of a Latin character base for that second case occurs in
some Western European sources including Riessler's work
[Riessl07]. While we have not found explicit substitutions for A
with Macron, we believe they might be found in practice. These
alternatives are not mapped together by Unicode Normalization Form
C (NFC) (or Normalization Form KC (NFKC)), so registries, and
possibly applications software, should exercise some care about
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these coding variations. However, U+0101 and U+0113 are Latin
Script characters so, if either is used, any tests on homogeneity
of the script within a label need to be made with care.
Similar issues may apply to other Kildin Sami characters
constructed with combining sequences.
The key references in Russian ([Anto90], [Kert86], [Kuru85]) all
propose slightly different character tables relative to each other
and to Riessler's list. Because the latter list appears to be more
comprehensive and to represent more recent scholarship, we have based
the tables in this document on it. We recommend, however, that
registries review these recommendations and the relevant papers
should registration requests for Kildin Sami actually appear.
Additional perspectives on Kildin Sami can be found on the Omniglot
Sami pages [OmniglotSaami].
2.5. Macedonian
Macedonian has 31 characters in the alphabet. This is eight in
addition to the basic set: U+0438, U+0458, U+0452, U+0459, U+045A,
U+045C, U+045F, U+0491, U+0455.
2.6. Montenegrin
According to the most recent, and now final, government specification
[MontenegrinChars], Montenegrin has 32 characters in its alphabet,
including two that have no precomposed forms in Unicode. This is
nine in addition to the basic set and two in addition to Bosnian and
Serbian: U+0437 U+0301, U+0438, U+0441 U+0301, U+0452, U+0458,
U+0459, U+045A, U+045B, U+045F.
See Bosnian, Section 2.1, above.
2.7. Russian
The current Russian alphabet has 33 characters, consisting of the
Base Cyrillic set plus an additional ten characters: U+0451, U+0438,
U+0439, U+0449, U+044A, U+044B, U+044C, U+044D, U+044E, U+044F.
2.8. Serbian
See Bosnian, Section 2.1, above.
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2.9. Ukrainian
The character list for modern Ukrainian has apparently not completely
stabilized. Some references claim 31 characters and therefore an
additional 8 characters to the Base Cyrillic set of 23. Others claim
33, adding U+0438 and U+0439 and replacing U+044A (Hard Sign) with
U+044C (Soft Sign), for a total of an additional 11 characters as
compared to the Base Cyrillic set. Unless better information is
available, the prudent registry should probably assume that all 34
characters are in use, i.e., the Base Cyrillic set plus U+0438,
U+0439, U+0454, U+0456, U+0457, U+0491, U+0449, U+044A, U+044C,
U+044E, U+044F.
3. Language-Based Tables
The registration strategy described in this document uses a table
that lists all characters allowed for input and any variants of those
characters. Note that the table lists all characters allowed, not
only the ones that have variants.
4. Table Processing Rules
The input to the process is called the "input label". The output of
the process is either failure (the input label cannot be registered
at all), or a registration bundle that contains one or more labels in
A-label form.
5. Table Format
The table in Appendix A consists of four columns. The first and
second identify the Cyrillic character, and the third and fourth
identify Latin or Greek characters that might be easily confused with
them visually. If both a Latin and Greek character are present, the
Greek one appears in the third and fourth columns on the subsequent
line (with "..." in the first column to indicate more information
about the character specified on the previous line). Variants needed
only because of case folding are shown with "+++" in the first
column, as noted in the table.
Each character in the table is given in the "U+" notation for Unicode
characters followed, in the next column, by its name as shown in the
Unicode Standard. For easy reference, the characters are listed in
the order in which they appear in the Unicode Standard.
The table does not, and any future revision MUST NOT, have more than
one entry for a particular base character.
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6. Steps after Registering an Input Label
A registry has at least three policy options for handling the cases
where the registration bundle has more than one label. These
options, and their key implications, are:
o Allocate all labels to the same registrant, making the zone
information identical to that of the input label.
This option will cause end users to be able to find names with
variants more easily, but will result in larger zone files. In
principle, the zone file could become so large that it could
negatively affect the ability of the registry to perform name
resolution.
o Block all labels so they cannot be registered in the future.
This option does not increase the size of the zone file, but it
may cause end users to not be able to find names with variants
that they would expect.
o Allocate some labels and block some other labels.
This option is likely to cause the most confusion with users
because including some variants will cause a name to be found, but
using other variants will cause the name to be not found.
With any of these three options, the registry MUST keep a database
that links each label in the registration bundle to the input label.
This link needs to be maintained so that changes in the non-DNS
registration information (such as the label's owner name and address)
are reflected in every member of the registration bundle as well.
7. Security Considerations
The information provided in this document may assist DNS zone
administrators and registrants in selecting names that are less
likely to be confused with others and in adopting policies that help
avoid confusion. It may also assist user-interface designers in
identifying possible areas of confusion so that they can better
protect users. The document otherwise has no consequences for the
security of the Internet.
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RFC 5992 Cyrillic IDNs October 2010
8. Acknowledgments
Support from Afilias for a major portion of this work is appreciated.
The material on Kildin Sami would not have been possible without the
efforts of Cary Karp for his help directly and his pointer to
Riessler's work [Riessl07] and from Vladimir Shadrunov and Sergey
Nikolaevich Teryoshkin for their own analyses and references
([Anto90], [Kert86], and [Kuru85]) and partial translations from
them. We are grateful for their efforts that facilitated treating it
nearly the same way as other actively used European languages that
use Cyrillic script.
Careful reading of late drafts of this document by Bill McQuillan,
Alexey Melnikov, and Peter Saint-Andre, identified a number of
editorial problems, some of which might not have been caught
otherwise.
9. References
9.1. Normative References
[RFC5895] Resnick, P. and P. Hoffman, "Mapping Characters
in Mapping Characters for Internationalized
Domain Names in Applications (IDNA) 2008",
RFC 5895, September 2010.
[Unicode52] The Unicode Consortium. The Unicode Standard,
Version 5.2.0, defined by: "The Unicode Standard,
Version 5.2.0", (Mountain View, CA: The Unicode
Consortium, 2009. ISBN 978-1-936213-00-9).
<http://www.unicode.org/versions/Unicode5.2.0/>.
9.2. Informative References
[Anto90] Antonova, A., "Primer for Sami schools first
grade: Sami language, 2nd edition", Leningrad:
Prosveshchenie, Leningrad department, 1990.
Published in Russian, no authoritative
translation is known.
[EU-registry] European Registry of Internet Domain Names
(EURid), ".eu Supported Characters",
January 2010, <http://www.eurid.eu/en/
eu-domain-names/technical-limitations/
supported-characters>.
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RFC 5992 Cyrillic IDNs October 2010
[Kert] Kertom, G., "Kildin dialect of the Sami
language". Published in Russian, no
authoritative translation is known.
[Kert86] Kertom, G., "Sami-Russian and Russian-Sami
dictionary: textbook for primary school pupils",
Leningrad: Prosveshchenie Leningrad Department,
1986. Published in Russian, no authoritative
translation is known.
[Kuru85] Kuruch, R., "Sami-Russian dictionary: eight
thousand words", Moscow: Russkiy yazyk, 1985.
Published in Russian, no authoritative
translation is known.
[MontenegrinChars] Crna Gora Ministarstvo prosvjete i nauke
(Ministry of Science and Education, Montenegro),
"Pravopis Crnogorskoga Jezika I", 2009,
<http://www.gov.me/files/1248442673.pdf>. In
Montenegrin, no known English translation. See
especially the table on page 8.
[OmniglotSaami] Ager, S., "Sami (Saami)", 2009,
<http://www.omniglot.com/writing/saami.htm>.
[RFC3743] Konishi, K., Huang, K., Qian, H., and Y. Ko,
"Joint Engineering Team (JET) Guidelines for
Internationalized Domain Names (IDN) Registration
and Administration for Chinese, Japanese, and
Korean", RFC 3743, April 2004.
[RFC4290] Klensin, J., "Suggested Practices for
Registration of Internationalized Domain Names
(IDN)", RFC 4290, December 2005.
[RFC4713] Lee, X., Mao, W., Chen, E., Hsu, N., and J.
Klensin, "Registration and Administration
Recommendations for Chinese Domain Names",
RFC 4713, October 2006.
[RFC5564] El-Sherbiny, A., Farah, M., Oueichek, I., and A.
Al-Zoman, "Linguistic Guidelines for the Use of
the Arabic Language in Internet Domains",
RFC 5564, February 2010.
[RFC5890] Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document
Framework", RFC 5890, August 2010.
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RFC 5992 Cyrillic IDNs October 2010
[RFC5892] Faltstrom, P., "The Unicode Code Points and
Internationalized Domain Names for Applications
(IDNA)", RFC 5892, August 2010.
[Riessl07] Riessler, M., "Kola Saami character chart
(draft)", November 2007.
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Appendix A. European Cyrillic Character Tables
These tables are constructed on the basis of the characters that can
actually occur in the DNS, i.e., those that are valid in U-labels as
defined in RFC 5890. If the characters that can be mapped into those
characters are to be considered instead, then the number of variants
would increase considerably. For example, while CYRILLIC SMALL
LETTER A (U+0430) and GREEK SMALL LETTER ALPHA (U+03B1) are readily
distinguished visually, their capital letter equivalents are not, so,
if case mappings such as those discussed in the IDNA2008 Mapping
document [RFC5895] are considered, the two small letters must be
considered variants of each other. Some of the variants have been
selected on the assumption that unusual fonts may be used and that
users will see what they expect to see; others, involving subtle
decorations but considered more far-fetched out of context, have not
been listed.
These additional, possibly required, variants are shown below with
"+++" in the first column of the table.
"..." in the first column is used to indicate more information about
the character specified on the previous line.
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Characters needed for European languages, other than Montenegrin and
Sami, written in Cyrillic.
+----------+--------------------------+---------+-------------------+
| Cyrillic | Unicode Name | Variant | Unicode Name |
| Char | | | |
+----------+--------------------------+---------+-------------------+
| U+0430 | CYRILLIC SMALL LETTER A | U+0061 | LATIN SMALL |
| | | | LETTER A |
| | | | |
| +++ | | U+03B1 | GREEK SMALL |
| | | | LETTER ALPHA |
| | | | |
| U+0431 | CYRILLIC SMALL LETTER BE | | |
| | | | |
| U+0432 | CYRILLIC SMALL LETTER VE | U+0062 | LATIN SMALL |
| | | | LETTER B |
| | | | |
| +++ | | U+03B2 | GREEK SMALL |
| | | | LETTER BETA |
| | | | |
| U+0433 | CYRILLIC SMALL LETTER | U+0072 | LATIN SMALL |
| | GHE | | LETTER R |
| | | | |
| +++ | | U+03B3 | GREEK SMALL |
| | | | LETTER GAMMA |
| | | | |
| U+0434 | CYRILLIC SMALL LETTER DE | | |
| | | | |
| +++ | | U+03B4 | GREEK SMALL |
| | | | LETTER DELTA |
| | | | |
| U+0435 | CYRILLIC SMALL LETTER IE | U+0065 | LATIN SMALL |
| | | | LETTER E |
| | | | |
| +++ | | U+03B5 | GREEK SMALL |
| | | | LETTER EPSILON |
| | | | |
| U+0436 | CYRILLIC SMALL LETTER | | |
| | ZHE | | |
| | | | |
| U+0437 | CYRILLIC SMALL LETTER ZE | | |
| | | | |
| U+0438 | CYRILLIC SMALL LETTER I | U+0075 | LATIN SMALL |
| | | | LETTER U |
| | | | |
| U+0439 | CYRILLIC SMALL LETTER | | |
| | SHORT I | | |
Sharikov, et al. Informational [Page 14]
RFC 5992 Cyrillic IDNs October 2010
| | | | |
| U+043A | CYRILLIC SMALL LETTER KA | U+006B | LATIN SMALL |
| | | | LETTER K |
| | | | |
| ... | | U+03BA | GREEK SMALL |
| | | | LETTER KAPPA |
| | | | |
| U+043B | CYRILLIC SMALL LETTER EL | | |
| | | | |
| +++ | | U+03BB | GREEK SMALL |
| | | | LETTER LAMBDA |
| | | | |
| U+043C | CYRILLIC SMALL LETTER EM | U+006D | LATIN SMALL |
| | | | LETTER M |
| | | | |
| +++ | | U+03BC | GREEK SMALL |
| | | | LETTER MU |
| | | | |
| U+043D | CYRILLIC SMALL LETTER EN | U+0048 | LATIN CAPITAL |
| | | | LETTER H |
| | | | |
| +++ | | U+0068 | LATIN SMALL |
| | | | LETTER H (in some |
| | | | fonts) |
| | | | |
| +++ | | U+03B7 | GREEK SMALL |
| | | | LETTER ETA |
| | | | |
| U+043E | CYRILLIC SMALL LETTER O | U+006F | LATIN SMALL |
| | | | LETTER O |
| | | | |
| ... | | U+03BF | GREEK SMALL |
| | | | LETTER OMICRON |
| | | | |
| U+043F | CYRILLIC SMALL LETTER PE | U+006E | LATIN SMALL |
| | | | LETTER N |
| | | | |
| ... | | U+03C0 | GREEK SMALL |
| | | | LETTER PI |
| | | | |
| U+0440 | CYRILLIC SMALL LETTER ER | U+0070 | LATIN SMALL |
| | | | LETTER P |
| | | | |
| ... | | U+03C1 | GREEK SMALL |
| | | | LETTER RHO |
| | | | |
| U+0441 | CYRILLIC SMALL LETTER ES | U+0063 | LATIN SMALL |
| | | | LETTER C |
Sharikov, et al. Informational [Page 15]
RFC 5992 Cyrillic IDNs October 2010
| | | | |
| U+0442 | CYRILLIC SMALL LETTER TE | U+0074 | LATIN SMALL |
| | | | LETTER T |
| | | | |
| +++ | | U+03C4 | GREEK SMALL |
| | | | LETTER TAU |
| | | | |
| U+0443 | CYRILLIC SMALL LETTER U | U+0079 | LATIN SMALL |
| | | | LETTER Y |
| | | | |
| +++ | | U+03C5 | GREEK SMALL |
| | | | LETTER UPSILON |
| | | | |
| U+0444 | CYRILLIC SMALL LETTER EF | U+03D5 | GREEK PHI SYMBOL |
| | | | |
| +++ | | U+03C6 | GREEK SMALL |
| | | | LETTER PHI |
| | | | |
| U+0445 | CYRILLIC SMALL LETTER HA | U+0078 | LATIN SMALL |
| | | | LETTER X |
| | | | |
| ... | | U+03C7 | GREEK SMALL |
| | | | LETTER CHI |
| | | | |
| U+0446 | CYRILLIC SMALL LETTER | | |
| | TSE | | |
| | | | |
| U+0447 | CYRILLIC SMALL LETTER | | |
| | CHE | | |
| | | | |
| U+0448 | CYRILLIC SMALL LETTER | | |
| | SHA | | |
| | | | |
| U+0449 | CYRILLIC SMALL LETTER | | |
| | SHCHA | | |
| | | | |
| U+044A | CYRILLIC SMALL LETTER | U+0062 | LATIN SMALL |
| | HARD SIGN | | LETTER B |
| | | | |
| U+044B | CYRILLIC SMALL LETTER | | |
| | YERU | | |
| | | | |
| U+044C | CYRILLIC SMALL LETTER | U+0062 | LATIN SMALL |
| | SOFT SIGN | | LETTER B |
| | | | |
| U+044D | CYRILLIC SMALL LETTER E | | |
| | | | |
| U+044E | CYRILLIC SMALL LETTER YU | | |
Sharikov, et al. Informational [Page 16]
RFC 5992 Cyrillic IDNs October 2010
| | | | |
| U+044F | CYRILLIC SMALL LETTER YA | | |
| | | | |
| U+0451 | CYRILLIC SMALL LETTER IO | U+00EB | LATIN SMALL |
| | | | LETTER E WITH |
| | | | DIAERESIS |
| | | | |
| U+0452 | CYRILLIC SMALL LETTER | | |
| | DJE | | |
| | | | |
| U+0453 | CYRILLIC SMALL LETTER | | |
| | GJE | | |
| | | | |
| U+0454 | CYRILLIC SMALL LETTER | U+03B5 | GREEK SMALL |
| | UKRAINIAN IE | | LETTER EPSILON |
| | | | |
| U+0455 | CYRILLIC SMALL LETTER | U+0073 | LATIN SMALL |
| | DZE | | LETTER S |
| | | | |
| U+0456 | CYRILLIC SMALL LETTER | U+0069 | LATIN SMALL |
| | BYELORUSSIAN-UKRAINIAN I | | LETTER I |
| | | | |
| +++ | | U+03B9 | GREEK SMALL |
| | | | LETTER IOTA |
| | | | |
| U+0457 | CYRILLIC SMALL LETTER | U+03CA | GREEK SMALL |
| | UKRAINIAN YI | | LETTER IOTA WITH |
| | | | DIALYTIKA |
| | | | |
| +++ | | U+00EF | LATIN SMALL |
| | | | LETTER I WITH |
| | | | DIAERESIS |
| | | | |
| U+0458 | CYRILLIC SMALL LETTER JE | U+006A | LATIN SMALL |
| | | | LETTER J |
| | | | |
| ... | | U+03F3 | GREEK LETTER YOT |
| | | | |
| U+0459 | CYRILLIC SMALL LETTER | | |
| | LJE | | |
| | | | |
| U+045A | CYRILLIC SMALL LETTER | | |
| | NJE | | |
| | | | |
| U+045B | CYRILLIC SMALL LETTER | | |
| | TSHE | | |
| | | | |
Sharikov, et al. Informational [Page 17]
RFC 5992 Cyrillic IDNs October 2010
| U+045C | CYRILLIC SMALL LETTER | | |
| | KJE | | |
| | | | |
| U+045D | CYRILLIC SMALL LETTER I | | |
| | WITH GRAVE | | |
| | | | |
| U+045E | CYRILLIC SMALL LETTER | | |
| | SHORT U | | |
| | | | |
| U+045F | CYRILLIC SMALL LETTER | | |
| | DZHE | | |
| | | | |
| U+0491 | CYRILLIC SMALL LETTER | U+0072 | LATIN SMALL |
| | GHE WITH UPTURN | | LETTER R |
| | | | |
| U+04C2 | CYRILLIC SMALL LETTER | | |
| | ZHE WITH BREVE | | |
+----------+--------------------------+---------+-------------------+
Additional characters needed for Montenegrin written in Cyrillic.
+--------------+-----------------------------+---------+------------+
| Cyrillic | Unicode Name | Variant | Unicode |
| Char | | | Name |
+--------------+-----------------------------+---------+------------+
| U+0437 + | CYRILLIC SMALL LETTER ZE | | |
| U+0301 | WITH ACUTE | | |
| | | | |
| U+0441 + | CYRILLIC SMALL LETTER ES | | |
| U+0301 | WITH ACUTE | | |
+--------------+-----------------------------+---------+------------+
Sharikov, et al. Informational [Page 18]
RFC 5992 Cyrillic IDNs October 2010
Additional characters needed for Kildin Sami written in Cyrillic.
+----------+---------------------+----------+-----------------------+
| Cyrillic | Unicode Name | Variant | Unicode Name |
| Char | | | |
+----------+---------------------+----------+-----------------------+
| U+0430 + | CYRILLIC SMALL | U+0101 | LATIN SMALL LETTER A |
| U+0304 | LETTER A WITH | | WITH MACRON |
| | MACRON | | |
| | | | |
| ... | | U+03B1 + | GREEK SMALL LETTER |
| | | U+0304 | ALPHA WITH MACRON |
| | | | |
| U+0435 + | CYRILLIC SMALL | U+0113 | LATIN SMALL LETTER E |
| U+0304 | LETTER IE WITH | | WITH MACRON |
| | MACRON | | |
| | | | |
| U+043E + | CYRILLIC SMALL | U+014D | LATIN SMALL LETTER O |
| U+0304 | LETTER O WITH | | WITH MACRON |
| | MACRON | | |
| | | | |
| ... | | U+03BF + | GREEK SMALL LETTER |
| | | U+0304 | OMICRON WITH MACRON |
| | | | |
| U+044B + | CYRILLIC SMALL | | |
| U+0304 | LETTER YERU WITH | | |
| | MACRON | | |
| | | | |
| U+044D + | CYRILLIC SMALL | | |
| U+0304 | LETTER E WITH | | |
| | MACRON | | |
| | | | |
| U+044E + | CYRILLIC SMALL | | |
| U+0304 | LETTER YU WITH | | |
| | MACRON | | |
| | | | |
| U+044F + | CYRILLIC SMALL | | |
| U+0304 | LETTER YA WITH | | |
| | MACRON | | |
| | | | |
| U+0451 + | CYRILLIC SMALL | U+00EB + | LATIN SMALL LETTER E |
| U+0304 | LETTER IO WITH | U0304 | WITH DIAERESIS AND |
| | MACRON | | MACRON |
| | | | |
| U+048B | CYRILLIC SMALL | | |
| | LETTER SHORT I WITH | | |
| | TAIL | | |
| | | | |
Sharikov, et al. Informational [Page 19]
RFC 5992 Cyrillic IDNs October 2010
| U+048D | CYRILLIC SMALL | | |
| | LETTER SEMISOFT | | |
| | SIGN | | |
| | | | |
| U+048F | CYRILLIC SMALL | | |
| | LETTER ER WITH TICK | | |
| | | | |
| U+04BB | CYRILLIC SMALL | U+0068 | LATIN SMALL LETTER H |
| | LETTER SHHA | | |
| | | | |
| U+04C6 | CYRILLIC SMALL | | |
| | LETTER EL WITH TAIL | | |
| | | | |
| U+04C8 | CYRILLIC SMALL | | |
| | LETTER EN WITH HOOK | | |
| | | | |
| U+04CA | CYRILLIC SMALL | | |
| | LETTER EN WITH TAIL | | |
| | | | |
| U+04CE | CYRILLIC SMALL | | |
| | LETTER EM WITH TAIL | | |
| | | | |
| U+04D3 | CYRILLIC SMALL | U+00E4 | LATIN SMALL LETTER A |
| | LETTER A WITH | | WITH DIAERESIS |
| | DIAERESIS | | |
| | | | |
| U+04E3 | CYRILLIC SMALL | U+016B | LATIN SMALL LETTER U |
| | LETTER I WITH | | WITH MACRON |
| | MACRON | | |
| | | | |
| U+04E7 | CYRILLIC SMALL | U+00F6 | LATIN SMALL LETTER O |
| | LETTER O WITH | | WITH DIAERESIS |
| | DIAERESIS | | |
| | | | |
| U+04ED | CYRILLIC SMALL | | |
| | LETTER E WITH | | |
| | DIAERESIS | | |
| | | | |
| U+04EF | CYRILLIC SMALL | | |
| | LETTER U WITH | | |
| | MACRON | | |
| | | | |
| U+04F1 | CYRILLIC SMALL | | |
| | LETTER U WITH | | |
| | DIAERESIS | | |
| | | | |
Sharikov, et al. Informational [Page 20]
RFC 5992 Cyrillic IDNs October 2010
| U+04F9 | CYRILLIC SMALL | | |
| | LETTER YERU WITH | | |
| | DIAERESIS | | |
+----------+---------------------+----------+-----------------------+
Authors' Addresses
Sergey Sharikov
Regtime Ltd
Kalinina str.,14
Samara 443008
Russia
Phone: +7(846) 979-9039
Fax: +7(846)979-9038
EMail: s.shar@regtime.net
Desiree Miloshevic
Afilias
Oxford Internet Institute, 1 St. Giles
Oxford OX1 3JS
United Kingdom
Phone: +44 7973 987 147
EMail: dmiloshevic@afilias.info
John C Klensin
1770 Massachusetts Ave, #322
Cambridge, MA 02140
USA
Phone: +1 617 491 5735
EMail: john-ietf@jck.com
Sharikov, et al. Informational [Page 21]