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Maximal Starting Repertoire Version 5 (MSR-5) Released

7 July 2021

The Internet Corporation for Assigned Names and Numbers (ICANN) today announced the release of the fifth version of the Maximal Starting Repertoire (MSR-5). This version is compatible with MSR-4, adding one code point each to the Latin and Devanagari script repertoires, and adding two code points to the Arabic script repertoire. MSR-5 also changes the Unicode base version from 6.3 to 11.0. Under the Procedure to Develop and Maintain the Label Generation Rules for the Root Zone in Respect of IDNA Labels, the MSR is the starting point for the work done by community-based Generation Panels that develop Root Zone Label Generation Rules (RZ-LGR) proposals for the relevant scripts.

RZ-LGRs provide a conservative mechanism to determine valid Internationalized Domain Name (IDN) top-level domains (TLDs) and their variant labels for the stable and secure operation of the Domain Name System root zone.

The contents of MSR-5 and a detailed rationale behind its development are available in the MSR-5 Overview and Rationale document. MSR-5 covers 28 scripts: Arabic, Armenian, Bengali, Cyrillic, Devanagari, Ethiopic, Georgian, Greek, Gujarati, Gurmukhi, Han, Hangul, Hebrew, Hiragana, Kannada, Katakana, Khmer, Lao, Latin, Malayalam, Myanmar, Oriya, Sinhala, Tamil, Telugu, Thaana, Tibetan, and Thai. For these scripts, MSR-5 shortlists 33,515 code points from Unicode version 11.0.

Until the next version, MSR-5 will be the foundation for any RZ-LGR versions developed. All future versions of the MSR and all versions of the RZ-LGR must retain full backwards compatibility.


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 nonprofit public benefit corporation with a community of participants from all over the world.