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Additional Second-Level Reference Label Generation Rules (LGRs) Published

LOS ANGELES – 13 January 2021 – The Internet Corporation for Assigned Names and Numbers (ICANN) today announced the publication of additional second-level reference Label Generation Rules (LGRs).

Second-level reference Label Generation Rules are published to improve the transparency and consistency of the Internationalized Domain Name (IDN) table review process that facilitates the registry operations of new generic top-level domains (gTLDs). The reference IDN tables are based on the Guidelines for Developing Reference Label Generation Rules (LGRs), which were finalized after community review. These reference LGRs will be used in reviewing IDN tables submitted by the gTLD registries, e.g., through the Registry Service Evaluation Policy (RSEP) process.

Additional reference LGRs have been developed based on the detailed analysis and finalized solutions completed by the script community for the Root Zone Label Generation Rules (RZ-LGRs). Seventeen second-level reference LGRs have been finalized and released after Public Comment proceedings, including the Bangla, Devanagari, Ethiopic, Georgian, Gujarati, Gurmukhi, Kannada, Khmer, Lao, Malayalam, Oriya, Tamil, and Telugu script-based LGRs, and the Arabic, Chinese, Hindi, and Thai language-based LGRs.

A total of 30 language-based reference LGRs and 13 script-based reference LGRs have been published. The remaining languages and scripts will be included in future releases as relevant community input becomes available.


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"""" is not an IDN."