SAC052 was published on 31 January 2012. All SSAC publications can be found at

Recommendation DescriptionCurrent Phase

Recommendation 1

Given the potential for user confusion and the currently unfinished work on string similarity and IDN variants, the SSAC recommends a very conservative approach to the delegation of single-character IDN top-level domains. In particular, until ICANN completes its work on user confusion/string similarity and IDN variants, the SSAC recommends:
  1. Delegation of all single-character IDN TLDs in all scripts should be disallowed by default.
  2. Exceptions may be made for some scripts, but only after careful consideration of potential confusability both within and across scripts. Such consideration should invite comments from the technical and linguistic community, and from ICANN's advisory committees.
  3. Single-character TLD applications in an exceptionally allowed script should be accepted only when there is clear evidence that there is no risk of user confusion. Each applied-for single-character TLD label must be explicitly examined across scripts to ensure that there is absolutely no possibility of user confusion within or across scripts.
  4. ICANN should consult with the technical and linguistic community to determine which scripts, if any, should be restricted with respect to the delegation of single character TLDs, and how any such restrictions should be defined, and how such restrictions may be relaxed if appropriate.
  5. ICANN should take into consideration the outcome of the IETF work on the creation of a concise specification of the TLD label syntax based on existing syntax documentation, extended minimally to accommodate IDNs.
  6. ICANN should consider adopting the following guidelines regarding its consideration of which scripts and code points could be accepted as exceptions:
    1. The code point must be PVALID according to IDNA2008.
    2. The code point is from one of the following Unicode categories: lower case letter (Ll), upper case letter (Lu), and other letter (Lo) as defined by the Unicode Standard.
    3. Some single-character IDN TLDs are composed of multiple Unicode code points, which may include non Lx-class code points. These should be subjected to a more stringent technical and confusability analysis, whose criteria should be well defined and made public.
    4. The script in which an exception is made and a single character IDN is allowed should not have characters that are intrinsically confusable with characters of another script (for example, Latin/Greek/Cyrillic, Lao/Thai, etc.).
    5. The existing and extended rules of confusability must be met. Single-character code points must explicitly be examined across scripts. Denial of a single character TLD application does not imply blocking of the script. Similarly, acceptance of a single-character TLD application does not imply acceptance of the script.
    6. If a script is allowed, a distinct and explicit specification of which subset of the script is available for single-character TLDs should be required prior to the acceptance of a single-character TLD application. By default all characters are disallowed, even when a script is allowed, and an explicit single-character-TLD-allowed list must be generated for each case.


Recommendation 2Because important relevant work on string similarity, IDN variant issues, and TLD label syntax is currently underway within ICANN, the IETF, and other bodies, ICANN should review the Findings of this report, and any policies that it adopts in response to Recommendation 1, no later than one year after the three work items mentioned above have been completed.


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