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Third Version of Label Generation Rules for the Root Zone (RZ-LGR-3) Released

LOS ANGELES – 10 July 2019 – Today, the Internet Corporation for Assigned Names and Numbers (ICANN) announced the release of the third version of Label Generation Rules for the Root Zone (RZ-LGR-3). These rules define a set of criteria for determining valid Internationalized Domain Name (IDN) labels for the Root Zone of the Domain Name System (DNS) and their variant labels.

A total of 16 scripts, out of the 28 scripts identified in the Maximal Starting Repertoire, are now integrated in the Label Generation Rules for the Root Zone (RZ-LGR). The first version (RZ-LGR-1), released in March 2016, integrated the Arabic script. The second version (RZ-LGR-2), released in August 2017, integrated five more scripts, including Ethiopic, Georgian, Khmer, Lao and Thai. RZ-LGR-3 integrates 10 additional scripts: Devanagari, Gujarati, Gurmukhi, Hebrew, Kannada, Malayalam, Oriya, Sinhala, Telugu, and Tamil. Armenian and Cyrillic script proposals have also been completed but have been deferred from integration until related script proposals are also finalized. The remaining scripts will be included in the future releases of RZ-LGR, as relevant proposals become available.

These label generation rules have been defined by the respective community-based Generation Panels and evaluated and integrated by the Integration Panel after the public comment period, following the Procedure to Develop and Maintain the Label Generation Rules for the Root Zone in Respect of IDNA Labels [PDF, 1.4 MB].


ICANN's mission is to help ensure a stable, secure, and unified global Internet. To reach another person on the Internet, you have to type an address into your computer - a name or a number. That address has to 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 and a community with participants from all over the world. ICANN and its community help keep the Internet secure, stable and interoperable. It also promotes competition and develops policy for the top-level of the Internet's naming system and facilitates the use of other unique Internet identifiers. For more information please visit:

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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."