Network Working Group A. El-Sherbiny Internet-Draft M. Farah Intended status: Informational UN-ESCWA Expires: April 24, 2009 I. Oueichek Syrian Telecom Establishment A. Al-Zoman SaudiNIC, CITC October 21, 2008 Linguistic Guidelines for the Use of Arabic Characters in Internet Domains draft-farah-adntf-ling-guidelines-02.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on April 24, 2009. Abstract This document constitutes technical specifications for the use of Arabic characters in Internet Domain names and provides linguistic guidelines for Arabic Domain Names. It addresses Arabic-specific linguistic issues pertaining to the use of Arabic language in domain names. El-Sherbiny, et al. Expires April 24, 2009 [Page 1] Internet-Draft Arabic Character Guidelines October 2008 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Arabic Language-Specific Issues . . . . . . . . . . . . . . . 4 2.1. Linguistic Issues . . . . . . . . . . . . . . . . . . . . 4 2.1.1. Diacritics (tashkeel) and Shadda . . . . . . . . . . . 5 2.1.2. Kasheeda or Tatweel (Horizontal Character Size Extension) . . . . . . . . . . . . . . . . . . . . . . 5 2.1.3. Character Folding . . . . . . . . . . . . . . . . . . 5 2.2. Supported Character Set . . . . . . . . . . . . . . . . . 6 2.3. Arabic Linguistic Issues Affected By Technical Constraints . . . . . . . . . . . . . . . . . . . . . . . 8 2.3.1. Numerals . . . . . . . . . . . . . . . . . . . . . . . 8 2.3.2. The Space Character . . . . . . . . . . . . . . . . . 9 3. Summary and Conclusion . . . . . . . . . . . . . . . . . . . . 9 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Normative References . . . . . . . . . . . . . . . . . . . 10 7.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11 Intellectual Property and Copyright Statements . . . . . . . . . . 12 El-Sherbiny, et al. Expires April 24, 2009 [Page 2] Internet-Draft Arabic Character Guidelines October 2008 1. Introduction The Internet Engineering Task Force (IETF) issued in March 2003 a set of RFCs for Internationalized Domain Names (IDN) [1],[2], [3] which were planned to become the de facto standard for all languages. In 2007 and 2008, new versions of the internet-drafts proposing the revisions to the IDNA protocol have been released and are as follows: o Internationalizing Domain Names for Applications (IDNA): Issues and Rationale [5] o Internationalizing Domain Names in Applications (IDNA): Protocol [6] o An IDNA problem in right-to-left scripts [7] o The Unicode Codepoints and IDN [8] Those documents are known collectively as "IDNA2008". This document constitutes a technical specification for the implementation of the IDN standards in the case of the Arabic Language. It will allow the use of standard language tables to write domain names in Arabic characters. Therefore, it should be considered as a logical extension to the IDN standards. It thus presents guidelines for the proper use of Arabic characters with the IDN standards. This document reflects the recommendations of the Arab Working Group on Arabic Domain Names (AWG-ADN) established by the League of Arab States (LAS), based on standardisation efforts of the United Nations Economic and Social Commission for Western Asia (UN-ESCWA) and its Internet- Draft, "Guidelines for an Arabic Internet Domain Name" [9]. It is also in full harmony with recent rigorous discussions that took place with the major language communities that also use the Arabic script in their languages. This document provides guidelines for the ways Arabic characters may be used for registering Internet Domain Names and how linguistic specific issues should be handled. A few rules are recommended for application at the protocol level. The key words "MUST", "REQUIRED", "SHOULD", "RECOMMENDED", and "MAY" in this document are to be interpreted as described in RFC 2119 [4]. Comments on this document are solicited and should be addressed to the working group's mailing list at ESCWA-ICTD@un.org and/or the author(s). El-Sherbiny, et al. Expires April 24, 2009 [Page 3] Internet-Draft Arabic Character Guidelines October 2008 2. Arabic Language-Specific Issues The main objective of the creation of Arabic Domain Names is to have a vehicle to increase Internet use amongst all strata of the Arabic- speaking communities. Furthermore, a non-user friendly Domain Name would further add to the ambiguity and the eccentricity of the Internet to the Arabic-speaking communities, thus contributing negatively to the spread of the Internet and leading to further isolation of these communities at the global level. Hence, there have been intensive efforts especially those spearheaded by Dr. Al-Zoman and contributed to by UN-ESCWA and its Arabic Domain Names Task Force (ADN-TF) to reach consensus on a multitude of linguistic issues with the following goals: o To define the accepted Arabic character set to be used for writing domain names in Arabic; which is the subject of this document. o To define the top-level domains of the Arabic domain name tree structure (i.e., Arabic gTLDs and ccTLDs). This goal will be handled in a separate document. The first meeting of the AWG-ADN, held in Damascus January-February 2005, gave special attention to the following: a. Simplification of the domain names, whenever possible, to facilitate the interaction of the Arabic user with the Internet. b. Adoption of solutions that do not lead to confusion either in reading or in writing, provided that this does not compromise the linguistic correctness of used words. c. Mixing Arabic and non-Arabic letters in the domain name label is not acceptable. 2.1. Linguistic Issues There are a number of linguistic issues that have been proposed with respect to the use of the Arabic language in domain names. This section will highlight some of them. This section is based on the papers of Dr. Al-Zoman [10] [11] and the report of the first meeting of AWG-ADN [12]. For details the reader is encouraged to review the references. El-Sherbiny, et al. Expires April 24, 2009 [Page 4] Internet-Draft Arabic Character Guidelines October 2008 2.1.1. Diacritics (tashkeel) and Shadda Tashkeel and Shadda are accent marks placed above or below Arabic letters to produce proper pronunciation. They are thus used to differentiate different meanings for different words with the same base characters. Consistent with the IDNA2008 proposals, neither Tashkeel nor Shadda are permitted in zone files. They can be supported or ignored, if necessary, in the user interface with local mappings and stripped before IDNA processing. The following are their Unicode presentations: U+064B ARABIC FATHATAN U+064C ARABIC DAMMATAN U+064D ARABIC KASRATAN U+064E ARABIC FATHA U+064F ARABIC DAMMA U+0650 ARABIC KASRA U+0651 ARABIC SHADDA U+0652 ARABIC SUKUN 2.1.2. Kasheeda or Tatweel (Horizontal Character Size Extension) Kasheeda (U+0640 ARABIC TATWEEL) must not be used in Arabic domain names and should be disallowed at the protocol level. 2.1.3. Character Folding Character folding is the process where multiple letters (that may have some similarity with respect to their shapes) are folded into one shape. Examples of such Arabic characters include: o Folding Teh Marbuta (U+0629) and Heh (U+0647) at the end of a word; o Folding different forms of Hamzah (U+0622, U+0623, U+0625, U+0627); o Folding Alef Maksura (U+0649) and Yeh (U+064A) at the end of a word; o Folding Waw with Hamzah Above (U+0624) and Waw (U+0648). El-Sherbiny, et al. Expires April 24, 2009 [Page 5] Internet-Draft Arabic Character Guidelines October 2008 With respect to the Arabic language, character folding is not acceptable because it changes the meaning of words and it is against the principle of spelling rules. Replacing a character valid for use in domain names with another character also valid for use in domain names, which may have a similar shape, will give a different meaning. This will lead to have only one word representing several words consisting of all the combinations of folded characters. Hence, the other words will be masked by a single word [10]. Mis-spelling or handwriting errors do occur leading to mixing different characters despite the fact that this is not the case in published and printed materials. One of the motivations of this effort is to preserve the language particularly with the spread of the globalization movement. Within this context, character folding is working against this motivation since it is going to have a negative affect on the principle and ethics of the language. Technology should work for preserving the language and not for destroying it. Thus, character folding should not be allowed. The case of digits is treated in a separate section below. 2.2. Supported Character Set A domain name to be written in Arabic must be composed of a sequence of the following UNICODE characters. These are based on UNICODE version 5.0. The tables below are constructed using an inclusion- based approach. Thus, characters that are not part of the table are prohibited. +---------+-------------------------------------+ | Unicode | Character Name | +---------+-------------------------------------+ | 0621 | ARABIC LETTER HAMZA | | 0622 | ARABIC LETTER ALEF WITH MADDA ABOVE | | 0623 | ARABIC LETTER ALEF WITH HAMZA ABOVE | | 0624 | ARABIC LETTER WAW WITH HAMZA ABOVE | | 0625 | ARABIC LETTER ALEF WITH HAMZA BELOW | | 0626 | ARABIC LETTER YEH WITH HAMZA ABOVE | | 0627 | ARABIC LETTER ALEF | | 0628 | ARABIC LETTER BEH | | 0629 | ARABIC LETTER TEH MARBUTA | | 062A | ARABIC LETTER TEH | | 062B | ARABIC LETTER THEH | | 062C | ARABIC LETTER JEEM | | 062D | ARABIC LETTER HAH | | 062E | ARABIC LETTER KHAH | | 062F | ARABIC LETTER DAL | | 0630 | ARABIC LETTER THAL | | 0631 | ARABIC LETTER REH | El-Sherbiny, et al. Expires April 24, 2009 [Page 6] Internet-Draft Arabic Character Guidelines October 2008 | 0632 | ARABIC LETTER ZAIN | | 0633 | ARABIC LETTER SEEN | | 0634 | ARABIC LETTER SHEEN | | 0635 | ARABIC LETTER SAD | | 0636 | ARABIC LETTER DAD | | 0637 | ARABIC LETTER TAH | | 0638 | ARABIC LETTER ZAH | | 0639 | ARABIC LETTER AIN | | 063A | ARABIC LETTER GHAIN | | 0641 | ARABIC LETTER FEH | | 0642 | ARABIC LETTER QAF | | 0643 | ARABIC LETTER KAF | | 0644 | ARABIC LETTER LAM | | 0645 | ARABIC LETTER MEEM | | 0646 | ARABIC LETTER NOON | | 0647 | ARABIC LETTER HEH | | 0648 | ARABIC LETTER WAW | | 0649 | ARABIC LETTER ALEF MAKSURA | | 064A | ARABIC LETTER YEH | | 0660 | ARABIC-INDIC DIGIT ZERO | | 0661 | ARABIC-INDIC DIGIT ONE | | 0662 | ARABIC-INDIC DIGIT TWO | | 0663 | ARABIC-INDIC DIGIT THREE | | 0664 | ARABIC-INDIC DIGIT FOUR | | 0665 | ARABIC-INDIC DIGIT FIVE | | 0666 | ARABIC-INDIC DIGIT SIX | | 0667 | ARABIC-INDIC DIGIT SEVEN | | 0668 | ARABIC-INDIC DIGIT EIGHT | | 0669 | ARABIC-INDIC DIGIT NINE | +---------+-------------------------------------+ Source: Supporting the Arabic Language in Domain Names [10] Table 1: CHARACTERS FROM UNICODE ARABIC TABLE (0600-06FF) El-Sherbiny, et al. Expires April 24, 2009 [Page 7] Internet-Draft Arabic Character Guidelines October 2008 +---------+-----------------+ | Unicode | Digit Name | +---------+-----------------+ | 0030 | DIGIT ZERO | | 0031 | DIGIT ONE | | 0032 | DIGIT TWO | | 0033 | DIGIT THREE | | 0034 | DIGIT FOUR | | 0035 | DIGIT FIVE | | 0036 | DIGIT SIX | | 0037 | DIGIT SEVEN | | 0038 | DIGIT EIGHT | | 0039 | DIGIT NINE | | 002D | HYPHEN-MINUS | | 002E | FULL STOP (Dot) | +---------+-----------------+ Source: Supporting the Arabic Language in Domain Names [11] Table 2: CHARACTERS FROM UNICODE BASIC LATIN TABLE (0000-007F) 2.3. Arabic Linguistic Issues Affected By Technical Constraints In this section, technical aspects of some linguistic issues are discussed. 2.3.1. Numerals In the Arab countries, there are two sets of numerical digits used: o Set I: (0, 1, 2, 3, 4, 5, 6, 7, 8, 9) mostly used in the western part of the Arab world. o Set II: (u+0660, u+0661, u+0662, u+0663, u+0664, u+0665, u+0666, u+0667, u+0668, u+0669) mostly used in the eastern part of the Arab world. Although visual differentiation between the Arabic zero (u+0660) and the dot (u+002E) in printed material is possible (the zero is larger in size and is printed higher than the dot), using it in domain names may lead to confusion. Folding set II to set I will eliminate the problem of the zero, in specific, and that of numerals in general. Both sets may be supported in the user interface but both must be folded to one set (Set I) at the preparation of internationalized strings (e.g., "stringprep") phase; i.e. storage of numerals in the zone file is done in ASCII format. El-Sherbiny, et al. Expires April 24, 2009 [Page 8] Internet-Draft Arabic Character Guidelines October 2008 2.3.2. The Space Character The space character is strictly disallowed in domain names, as it is a control character. Instead, the hyphen (Al-sharta) (i.e.u+02D) is proposed as a separator between Arabic words to avoid confusion that can take place if the words are typed without a separator, unlike in ASCII. It is acceptable to use the hyphen to separate between words within the same domain name label. 3. Summary and Conclusion The proposed guidelines are in full accordance with the IETF IDN standards and take into account Arabic language-specific issues within a compromise between grammatical rules of the Arabic language and the ease of use of the language on the Internet. 4. Security Considerations No particular security considerations could be identified regarding the use of Arabic characters in writing domain names. In particular, any potential visual confusion between different character strings is avoided using the guidelines proposed in this document. 5. IANA Considerations This document has no action for IANA. 6. Acknowledgments ESCWA ICT Division provided support and funding for the development of this document with the objective of reaching a standard for a comprehensive Arabic Domain Names. Thanks are due to SaudiNIC for its continuous efforts in supporting the development of Arabic Domain Names. John Klensin provided some editing help with the document. El-Sherbiny, et al. Expires April 24, 2009 [Page 9] Internet-Draft Arabic Character Guidelines October 2008 7. References 7.1. Normative References [1] Faltstrom, P., Hoffman, P., and A. Costello, "Internationalizing Domain Names in Applications (IDNA)", RFC 3490, March 2003. [2] Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN)", RFC 3491, March 2003. [3] Costello, A., "Punycode: A Bootstring encoding of Unicode for Internationalized Domain Names in Applications (IDNA)", RFC 3492, March 2003. [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. 7.2. Informative References [5] Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions, Background and Rationale", draft-ietf-idnabis-rationale-02 (work in progress), September 2008. [6] Klensin, J., "Internationalized Domain Names in Applications (IDNA): Protocol", draft-ietf-idnabis-protocol-05 (work in progress), September 2008. [7] Alvestrand, H. and C. Karp, "An updated IDNA criterion for right-to-left scripts", draft-ietf-idnabis-bidi-02 (work in progress), July 2008. [8] Faltstrom, P., "The Unicode Codepoints and IDNA", draft-ietf-idnabis-tables-02 (work in progress), July 2008. [9] United Nations Economic and Social Commission for Western Asia (UN-ESCWA), "Guidelines for an Arabic Domain Name System (ADNS)", Internet-Draft farah-adntf-adns-guidelines-03.txt, November 2007. [10] Al-Zoman, A., "Supporting the Arabic Language in Domain Names", October 2003, . [11] Al-Zoman, A., "Arabic Top-Level Domains", July 2003. Paper presented in EGM on promotion of Digital Arabic Content, the United Nations, ESCWA, Beirut El-Sherbiny, et al. Expires April 24, 2009 [Page 10] Internet-Draft Arabic Character Guidelines October 2008 [12] League of Arab States, "Report of the first meeting of AWG-ADN, Damascus", February 2005, . This document is in Arabic. Authors' Addresses Ayman El-Sherbiny Information and Communication Technology Division ESCWA UN-House P.O. Box 11-8575 Beirut Lebanon Email: El-sherbiny@un.org Mansour Farah Information and Communication Technology Division ESCWA UN-House P.O. Box 11-8575 Beirut Lebanon Email: farah14@un.org Ibaa Oueichek Syrian Telecom Establishment Damascus Syria Email: oueichek@scs-net.org Abdulaziz H. Al-Zoman, PhD SaudiNIC, General Directorate of Internet Services IT Sector, CITC King Abdulaziz City for Science and Technology PO Box 6086 Riyadh 11442 Saudi Arabia Email: azoman@citc.gov.sa El-Sherbiny, et al. Expires April 24, 2009 [Page 11] Internet-Draft Arabic Character Guidelines October 2008 Full Copyright Statement Copyright (C) The IETF Trust (2008). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. 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