Internet Corporation for Assigned Names and Numbers

An Important Step Toward the Implementation of IDN Top-Level Domains: New Versions of IDNA Protocol Revision Proposals Posted

26 November 2007

Revised papers of the technical standards that define the implementation of IDNs — the standards are called IDNA — were recently released via the IETF editors. These revisions are an important step toward the delegation of IDN top-level domains.

An informal expert panel, working as what the IETF calls a "design team," evaluated experiences gained in the implementation of the previous version of IDNA since its introduction in 2003, and identified several key areas of future work. These key areas were described in several documents that triggered a formal revision of the IDNA protocol. New versions of the internet-drafts proposing the revisions to the IDNA protocol have been released and are as follows:

The core components in the revision effort include:

  • definition of valid IDN labels, an inclusion-based model that clearly defines which characters will be available for IDNs (the current model is exclusion-based), and recognizes the implications of the Unicode handling of various scripts on use in IDNs;
  • elimination of confusing and non-reversible character mappings;
  • fixing an error in right-to-left error in Stringprep (a profile used to prepare IDNs in the IDNA protocol ), and eliminating Unicode version dependencies, thereby permitting more scripts to be used in IDNs now and in the future.

The issues with the current IDN model that led to these revisions are discussed in RFC4690. This RFC discusses specific character issues where the same script is used in different languages, issues related to cases where languages can be expressed by using more than one script, issues involving bi-directional cases, and issues concerning the topic of visually confusing characters.

ICANN urges the Internet technical community to take part in the final stages of this development work by reviewing this documentations and constructively commenting on it. The review is moving forward in accordance with standard IETF processes. The intention is to finalize this work and publish the new IDNA standard within the next two months.

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