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Policy for IDN Code Points

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CC Policy

1. Part I: Permissible Code Points 
2. Part II: Restricted Code Points 
3. Part III: Further Restrictions on Commingling of Scripts

1. Part I: Permissible Code Points

The implementation of IDN registration for the .CC Top Level Domain strictly follows the guidelines set forth in the following RFC documents by the Internet Engineering Task Force (IETF):

1. RFC 3490 describes IDNA which is the IETF standard for IDNs.
2. RFC 3491 and RFC 3454 describe the algorithms for normalizing IDNs.
3. RFC 3492 describes punycode, the ASCII encoding algorithm used to make IDNs compatible with the DNS.
4. The .CC registries allow registration of code points included in Unicode 3.2 subject to the restrictions in the above RFC documents.

2. Part II: Restricted Code Points

The .CC registry implements certain restrictions on code points beyond that allowed by the RFC documents:

• Code points introduced after Unicode 3.2 are prohibited.
• The following special characters and symbols are prohibited 
  

• IDN objects must be properly encoded in punycode, and start with the “xn--“ prefix as identifier indicating they are IDNs.
• Domain names that start with 2 ASCII letters immediately followed by 2 consecutive hyphens other than “xn--“ are not allowed for registrations.

3. Part III: Further Restrictions on Commingling of Scripts

The Rule 
As a rule, the .CC registry rejects the commingling of code points from different Unicode blocks.  That is, if an IDN contains code points from any two or more Unicode blocks, then that IDN registration is rejected. For example, letter(s) from Latin alphabets cannot be used with letter(s) from Cyrillic in an IDN. All code points within an IDN must come from the same single Unicode block.

The Exception: 
An exception to this rule is made for well-defined languages which want to allow this commingling in certain circumstances.  For instance, symbols for the Korean language are contained in the Unicode block called “Hangul Syllables” (u+AC00 – u+D7AF).  However, Korean commonly uses basic Latin characters as well, so National Internet Development Agency of Korea (NIDA, the .kr ccTLD registry) developed a language table which includes the “Hangul Syllables” as well as lowercase Latin letters (a-z), numbers (0-9) and the hyphen character.  Normally these characters would not be allowed to commingle in a single domain name, but IDN objects marked with the “KOR” language tag for Korean can safely contain the code points above.

The .CC Top Level Domain maintains language definitions for the following languages:

IDN registrations marked with one of the above language tags will be checked against that languages definition to determine validity. IDN registrations marked with a language not in the above table must meet the zero-commingling conditions of the original rule.