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Fourth Version of Root Zone Label Generation Rules (RZ-LGR-4) Published

LOS ANGELES – 6 November 2020 – The Internet Corporation for Assigned Names and Numbers (ICANN) today announced the publication of the fourth version of Label Generation Rules for the Root Zone (RZ-LGR-4). Root Zone Label Generation Rules (RZ-LGR) define a set of rules to determine valid Internationalized Domain Name (IDN) labels for the root zone of the Domain Name System (DNS) and their variant labels.

RZ-LGR-4 integrates 18 scripts, adding Chinese and Bangla scripts in this version, in addition to Arabic, Devanagari, Ethiopic, Georgian, Gujarati, Gurmukhi, Hebrew, Kannada, Khmer, Lao, Malayalam, Oriya, Sinhala, Tamil, Telugu, and Thai. These rules were developed using the proposals submitted by the Generation Panels (GPs) formed for these scripts, which were finalized after Public Comment proceedings. The Armenian and Cyrillic script proposals have also been completed by the respective GPs but have been deferred from integration by the Integration Panel until proposals for related scripts are also finalized.

RZ-LGR development follows the Procedure to Develop and Maintain the Label Generation Rules for the Root Zone in Respect of IDNA Labels. A total of 28 scripts have been identified in the Maximal Starting Repertoire for inclusion in RZ-LGR. The remaining scripts will be included in future releases of RZ-LGR as relevant proposals become available from the community.


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."