RFC 0000 IDNA Unicode Reviews March 2020
Doe Standards Track [Page]
Internet Engineering Task Force (IETF)
Standards Track
J. Doe

RFC 0000



The standards for Internationalized Domain Names in Applications (IDNA) require a review of each new version of Unicode to determine whether incompatibilities with prior versions or other issues exist and, where appropriate, to allow the IETF to decide on the trade-offs between compatibility with prior IDNA versions and compatibility with Unicode going forward. That requirement, and its relationship to tables maintained by IANA, has caused significant confusion in the past. This document makes adjustments to the review procedure based on experience and updates IDNA, specifically RFC 5892, to reflect those changes and to clarify the various relationships involved. It also makes other minor adjustments to align that document with experience.

Status of This Memo

This is an Internet Standards Track document.

This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 7841.

Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc0000.

Table of Contents

1. Review Model Part I: Algorithmic Comparison


(i) Section 5.1 of [RFC5892]

(ii) Section 5.1 of RFC 5892 [RFC5892]

(iii) Section 5.1 of RFC 5892

(iv) Section 5.1 of RFC 5892 [RFC5892]

is the description of the process for creating the initial IANA tables. It is noteworthy that, while it can be read as strongly implying new reviews and new tables for versions of Unicode after 5.2, it does not explicitly specify those reviews or, e.g., the timetable for completing them. It also indicates that incompatibilities are to be "flagged for the IESG" but does not specify exactly what the IESG is to do about them and when. For reasons related to the other type of review and discussed below, only one review was completed, documented [RFC6452], and a set of corresponding new tables installed. That review, which was for Unicode 6.0, found only three incompatibilities; the consensus was to ignore them (not create exceptions in IDNA2008) and to remain consistent with computations based on current (Unicode 6.0) properties rather than preserving backward compatibility within IDNA. The 2018 review (for Unicode 11.0 and versions in between it and 6.0) [IDNA-Unicode12] also concluded that Unicode compatibility, rather than IDNA backward compatibility, should be maintained. That decision was partially driven by the long period between reviews and the concern that table calculations by others in the interim could result in unexpected incompatibilities if derived property definitions were then changed.

2. References

2.1. Normative References

RFC Errata, Erratum ID 3312, RFC 5892, <https://www.rfc-editor.org/errata/eid3312>.
IANA, "IDNA Rules and Derived Property Values", <https://www.iana.org/assignments/idna-tables>.
Faltstrom, P., Ed., "The Unicode Code Points and Internationalized Domain Names for Applications (IDNA)", RFC 5892, DOI 10.17487/RFC5892, , <https://www.rfc-editor.org/info/rfc5892>.
Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, , <https://www.rfc-editor.org/info/rfc8126>.
The Unicode Consortium, "The Unicode Standard (Current Version)", , <http://www.unicode.org/versions/latest/>.
The Unicode Consortium, "The Unicode Standard Version 11.0", Section 3.5, , <https://www.unicode.org/versions/Unicode11.0.0/>.

2.2. Informative References

Internet Architecture Board (IAB), "IAB Statement on Identifiers and Unicode", , <https://www.iab.org/documents/correspondence-reports-documents/2018-2/iab-statement-on-identifiers-and-unicode/>.
Internet Architecture Board (IAB), "IAB Statement on Identifiers and Unicode 7.0.0", , <https://www.iab.org/documents/correspondence-reports-documents/2015-2/iab-statement-on-identifiers-and-unicode-7-0-0/>.
Internet Corporation for Assigned Names and Numbers (ICANN), "Proposed IANA SLAs for Publishing LGRs/IDN Tables", , <https://www.icann.org/public-comments/proposed-iana-sla-lgr-idn-tables-2019-06-10-en>.
Faltstrom, P., "IDNA2008 and Unicode 11.0.0", Work in Progress, Internet-Draft, draft-faltstrom-unicode11-08, , <https://tools.ietf.org/html/draft-faltstrom-unicode11-08>.
Faltstrom, P., "IDNA2008 and Unicode 12.0.0", Work in Progress, Internet-Draft, draft-faltstrom-unicode12-00, , <https://tools.ietf.org/html/draft-faltstrom-unicode12-00>.
Klensin, J. and P. Faltstrom, "IDNA Update for Unicode 7.0 and Later Versions", Work in Progress, Internet-Draft, draft-klensin-idna-5892upd-unicode70-05, , <https://tools.ietf.org/html/draft-klensin-idna-5892upd-unicode70-05>.
Klensin, J. and A. Freytag, "Internationalized Domain Names in Applications (IDNA): Registry Restrictions and Recommendations", Work in Progress, Internet-Draft, draft-klensin-idna-rfc5891bis-05, , <https://tools.ietf.org/html/draft-klensin-idna-rfc5891bis-05>.
Alvestrand, H., "Tags for the Identification of Languages", RFC 1766, DOI 10.17487/RFC1766, , <https://www.rfc-editor.org/info/rfc1766>.
Alvestrand, H., "Content Language Headers", RFC 3282, DOI 10.17487/RFC3282, , <https://www.rfc-editor.org/info/rfc3282>.
Hoffman, P. and M. Blanchet, "Preparation of Internationalized Strings ("stringprep")", RFC 3454, DOI 10.17487/RFC3454, , <https://www.rfc-editor.org/info/rfc3454>.
Faltstrom, P., Hoffman, P., and A. Costello, "Internationalizing Domain Names in Applications (IDNA)", RFC 3490, DOI 10.17487/RFC3490, , <https://www.rfc-editor.org/info/rfc3490>.
Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Profile for Internationalized Domain Names (IDN)", RFC 3491, DOI 10.17487/RFC3491, , <https://www.rfc-editor.org/info/rfc3491>.
Yergeau, F., "UTF-8, a transformation format of ISO 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, , <https://www.rfc-editor.org/info/rfc3629>.
Klensin, J., Faltstrom, P., Karp, C., and IAB, "Review and Recommendations for Internationalized Domain Names (IDNs)", RFC 4690, DOI 10.17487/RFC4690, , <https://www.rfc-editor.org/info/rfc4690>.
Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646, , <https://www.rfc-editor.org/info/rfc5646>.
Klensin, J., "Internationalized Domain Names for Applications (IDNA): Definitions and Document Framework", RFC 5890, DOI 10.17487/RFC5890, , <https://www.rfc-editor.org/info/rfc5890>.
Klensin, J., "Internationalized Domain Names for Applications (IDNA): Background, Explanation, and Rationale", RFC 5894, DOI 10.17487/RFC5894, , <https://www.rfc-editor.org/info/rfc5894>.
Faltstrom, P., Ed. and P. Hoffman, Ed., "The Unicode Code Points and Internationalized Domain Names for Applications (IDNA) - Unicode 6.0", RFC 6452, DOI 10.17487/RFC6452, , <https://www.rfc-editor.org/info/rfc6452>.

Author's Address

John Doe