Label Generation Rulesets

A Label Generation Ruleset (LGR) defines which characters may be used in a domain name for a given script or language, and which labels are considered variants of one another. Registries use them to decide what may be registered in a zone, and to identify the labels that must be withheld or reserved alongside a registration.

Rulesets are published as XML in the format defined by RFC 7940. Each one can be downloaded for use in software, or inspected interactively.

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  Root Zone Ruleset

  The rules determining which labels may be used as internationalised top-level domains in the DNS root zone, and which labels are variants of one another. Each script is maintained as its own element ruleset; the Common ruleset integrates them all.

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  Reference Rulesets

  Reference rulesets a registry can adopt as the basis of its own second-level policy. These are templates rather than operational rules: each carries instructions for adapting it to a zone and depositing the result in the IANA Repository of IDN Practices.

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  Ruleset Repository

  The rulesets and legacy tables deposited by top-level domain registries, describing the policies actually in force in their zones.