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Recommendations for Managing Internationalized Domain Name Variant Top-Level Domains Published

LOS ANGELES – 5 February 2019 – The Internet Corporation for Assigned Names and Numbers (lCANN) today announced the release of the Recommendations for Managing Internationalized Domain Name (IDN) Variant Top-Level Domains (TLDs) as a collection of six documents. These recommendations have been developed by the ICANN organization with community feedback received during the Public Comment period.

  1. IDN Variant TLD Implementation – Executive Summary [PDF, 70 KB]
  2. IDN Variant TLD Implementation – Motivation, Premises and Framework [PDF, 391 KB]
  3. IDN Variant TLD Implementation – Recommendations and Analysis [PDF, 382 KB]
  4. IDN Variant TLD Implementation – Rationale for RZ-LGR [PDF, 497 KB]
  5. IDN Variant TLD Implementation – Risks and their Mitigation [PDF, 230 KB]
  6. IDN Variant TLD Implementation – Appendices (A: Definitions, B: Use of ROID, C: Limiting Allocated Variant TLDs) [PDF, 530 KB]

While the Internet community has often expressed a need for IDN variant TLDs, appropriate technical details and procedures have not been in place to support these. The ICANN Board resolved on 25 September 2010 that "no variants of gTLDs will be delegated ... until appropriate variant management solutions are developed." Subsequent work by the ICANN org and the community on the analysis of issues for Arabic [PDF, 1.06 MB], Chinese [PDF, 2.86 MB], Cyrillic [PDF, 1 MB], Devanagari [PDF, 461 KB], Greek [PDF, 354 KB], and Latin [PDF, 425 KB] scripts in 2011, integrated in the Integrated Issues Report (IIR) [PDF, 2.14 MB] (2012), identified two challenges: (i) there is no accepted definition for variant TLDs, and (ii) there is no 'variant management' mechanism for TLDs.

For the first issue, the Root Zone Label Generation Rules (RZ-LGR) Procedure [PDF, 1.39 MB] was developed with the support of the community and adopted by the ICANN Board on 11 April 2013 for implementation. The Procedure has been implemented and RZ-LGR has been developed for six scripts, while other scripts are being added as their proposals are finalized by the relevant script communities. This enables a transparent and predictable mechanism for identification of variant labels going forward.

For the second issue, the ICANN org has undertaken a detailed examination to develop a set of recommendations on variant management mechanisms for TLDs, which have been finalized based on the community input. The recommendations, in summary, include the following:

  1. RZ-LGR must be the only source for valid TLDs and their variant labels.
  2. IDN variant TLDs {t1, t1v1, …} must be allocated to same entity.
  3. Same label under IDN variant TLDs s1.{t1, t1v1, …} must be registered to the same entity.
  4. Second-level variant labels under IDN variant TLDs {s1, s1v1, …}.{t1, t1v1, …} must be registered to the same entity.
  5. Second-level IDN tables offered under IDN variant TLDs must be harmonized.
  6. IDN variant label allocatable or activated under IDN variant TLDs may not necessarily be the same.
  7. The registry service providers must be the same for IDN variant TLDs.
  8. Existing policies and associated procedures for TLDs must be updated to accommodate the recommendations for IDN variant TLDs.
  9. All remaining existing TLD policies must apply to IDN variant TLDs, unless otherwise identified.

These recommendations and associated analysis in the six documents will be presented for further consideration to the ICANN Board, anticipated in March 2019.

About ICANN

ICANN's mission is to help ensure a stable, secure, and unified global Internet. To reach another person on the Internet, you need to type an address – a name or a number – into your computer or other device. That address must be unique so computers know where to find each other. ICANN helps coordinate and support these unique identifiers across the world. ICANN was formed in 1998 as a not-for-profit public-benefit corporation with a community of participants from all over the world.


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Domain Name System
Internationalized Domain Name ,IDN,"IDNs are domain names that include characters used in the local representation of languages that are not written with the twenty-six letters of the basic Latin alphabet ""a-z"". An IDN can contain Latin letters with diacritical marks, as required by many European languages, or may consist of characters from non-Latin scripts such as Arabic or Chinese. Many languages also use other types of digits than the European ""0-9"". The basic Latin alphabet together with the European-Arabic digits are, for the purpose of domain names, termed ""ASCII characters"" (ASCII = American Standard Code for Information Interchange). These are also included in the broader range of ""Unicode characters"" that provides the basis for IDNs. The ""hostname rule"" requires that all domain names of the type under consideration here are stored in the DNS using only the ASCII characters listed above, with the one further addition of the hyphen ""-"". The Unicode form of an IDN therefore requires special encoding before it is entered into the DNS. The following terminology is used when distinguishing between these forms: A domain name consists of a series of ""labels"" (separated by ""dots""). The ASCII form of an IDN label is termed an ""A-label"". All operations defined in the DNS protocol use A-labels exclusively. The Unicode form, which a user expects to be displayed, is termed a ""U-label"". The difference may be illustrated with the Hindi word for ""test"" — परीका — appearing here as a U-label would (in the Devanagari script). A special form of ""ASCII compatible encoding"" (abbreviated ACE) is applied to this to produce the corresponding A-label: xn--11b5bs1di. A domain name that only includes ASCII letters, digits, and hyphens is termed an ""LDH label"". Although the definitions of A-labels and LDH-labels overlap, a name consisting exclusively of LDH labels, such as""icann.org"" is not an IDN."