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First Version of Label Generation Rules for the Root Zone Released

ICANN is pleased to announce that the first version of Label Generation Rules for the Root Zone (LGR-1) has been released. LGR-1 is designed to be the first installment of a conservative set of rules to determine the validity and variants of labels for the DNS Root Zone. Read the blog to learn more about the community's efforts to further promote a multilingual Internet.

LGR-1 was developed following the Procedure to Develop and Maintain the Label Generation Rules for the Root Zone in Respect of IDNA Labels [PDF, 1.39 MB]. It contains code points, variants and rules for the Arabic script, defined by the community and evaluated by the Integration Panel. As additional script LGR proposals are approved and meet the requirements for integration, new versions of the integrated LGR will be released. Once finalized, each version can be applied mechanically to determine the validity of an applied-for top-level domain label and the maximal set of its allocatable variant labels for the scripts supported. Further mechanisms are being developed to determine which of these allocatable variant labels will actually be allocated to those who have applied for top-level domains.


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."