IESG Statement on IDN (fwd)

Claudio Allocchio Claudio.Allocchio a GARR.IT
Mer 12 Feb 2003 10:12:30 CET


Claudio Allocchio             G   A   R   R          Claudio.Allocchio a
                        Project Technical Officer
tel: +39 040 3758523      Italian Academic and       G=Claudio; S=Allocchio;
fax: +39 040 3758565        Research Network         P=garr; A=garr; C=it;

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---------- Forwarded message ----------
Date: Tue, 11 Feb 2003 21:04:10 -0500
From: The IESG <iesg-secretary a>
To: IETF-Announce:  ;
Subject: IESG Statement on IDN

IESG Statement on IDN:

 IDNA [IDNA] specifies an encoding of characters in the Unicode
 character repertoire [UNICODE] which is backwards-compatible with the
 current definition of hostnames. This implies that domain names
 encoded according to IDNA will be able to be transported between
 peers using any existing protocol, including DNS.

 IDNA, through its requirement of Nameprep [NAMEPREP], uses equivalence
 tables that are based only on the characters themselves; no attention
 is paid to the intended language (if any) for the domain name. However,
 for many domain names, the intended language of one or more parts of
 the domain name actually does matter to the users.

 Similarly, many names cannot be presented and used without ambiguity
 unless the scripts to which their characters belong are known. In both
 cases, this additional information should be of concern to the registry.

 If there are no constraints on registration in a zone, people can
 register combinations of characters in a manner that increases the
 risk of misunderstandings, cybersquatting, and other forms of
 confusion. A somewhat similar situation existed before the introduction
 of IDNA exemplified by domain names such as and
 (note that the latter domain has the digit "1" instead of the letter

 For some human languages, there are strings of characters that have
 equivalent or near-equivalent meanings. When someone registers a name
 containing such a string, the registry might want to automatically
 generate a list of semantically or visually equivalent strings and
 suggest that they also be registered. Further, some registries might
 want to prevent particular characters for language-based reasons.

 Some registries, in particular the gTLD ones, are not naturally part
 of any specific language group. In these cases, extra care must be
 taken not to create unacceptable problems for any of the languages that
 might be used.

 It is suggested that a registry act conservatively when starting to
 accept IDNA-based domain names. Equivalences are very hard (if not
 impossible) to define after registration has started. Assume that the
 labels "x" and "y" at first are different, but later the tables for the
 registry are changed so that "x" and "y" are then treated as being the
 same. If and both were already registered
 to different registrants, it is unclear which of them has to withdraw
 the registration, how that selection process done, and so on. Thus,
 having complete, publicly-stated policies before accepting
 registration will lead to a much more stable registration process.

 There are also other problems that we know to be difficult when
 dealing with IDNA-based domain names, for instance when to convert them
 between their display format and their wire format, how to deal with
 display formats on systems that do not support all of Unicode 3.2, and
 how to deal with the problem of domain names in one format showing up
 where names in the other format was expected by protocols or by people.
 These problems are largely outside the scope of the IDNA standards
 themselves, but they are of concern to anyone attempting to implement
 the IDNA standard in products. See the IDNA specification for more

 The use of display-format IDNA-based domain names in other protocols
 is not yet part of any standard; implementors are admonished to use
 the wire format, i.e. ASCII-encoded, of the name until protocol
 updates allowing the use of display format, e.g. Unicode-based
 international character/glyph, are standardized.

 [IDNA] "Internationalizing Domain Names in Applications (IDNA)",

 [NAMEPREP] "Nameprep: A Stringprep Profile for Internationalized Domain
 Names", draft-ietf-idn-nameprep.

 [UNICODE] The Unicode Consortium. The Unicode Standard, Version 3.2.0
 is defined by The Unicode Standard, Version 3.0 (Reading, MA,
 Addison-Wesley, 2000. ISBN 0-201-61633-5), as amended by the Unicode
 Standard Annex #27: Unicode 3.1 (
 and by the Unicode Standard Annex #28: Unicode 3.2

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