Proposed Charter for the IDNAbis Working Group

Vint Cerf vint at
Wed Mar 26 12:08:52 CET 2008

Ladies and gentlemen,

on the basis of the several weeks of exchanges on this list, a draft  
charter for the IDNAbis Working Group has emerged. It is enclosed  
below and as the proposed chair, I ask the participants in the IDNA- 
update distribution list to confirm adoption of the charter. If there  
are no strong objections, I request that Area Directors Lisa  
Dusseault and Chris Newman put the charter forward to the IESG for  
its approval. Needless to say, I am grateful to all of you who have  
contributed to the production of this charter in the past several  
weeks, most particularly john klensin, paul hoffman, martin duerst,  
patrik fältström, mark davis, harald alvestrand, stephane bortzmeyer,  
erik van der poel, jefsey morfin, simon josefsson, lisa dusseault,  
among many others. Apologies if I missed adding your name to the list  
- it was starting to get kind of long.

I look forward to what I hope will be rapid progress of this working  
group towards the production of RFCs documenting improvements to the  
IDNA protocols.

Vint Cerf



Chair(s):  Vinton G. Cerf

Applications Area Directors:

Lisa Dusseault (ldusseault at
Chris Newman (Chris.Newman at

Applications Area Advisor:

Lisa Dusseault (ldusseault at

Mailing List:
General Discussion: idna-update at
To Subscribe:


The original Internationalized Domain Name (IDN) WG set the
requirements for international characters in domain names in
RFC3490, RFC3491 and RFC3492 in 2002 (published in 2003).
These documents depend on RFC 3454 and were tied to Unicode
version 3.2.  An update to the current version (5.x) is
required to accommodate additional scripts.  In addition,
experience has shown a number of real or perceived defects or
inadequacies with the protocol.

This WG is chartered to untie IDNA from specific versions of
Unicode using algorithms that define validity based on Unicode
properties.  It is recognized that some explicit exceptions may
be necessary in any case, but attempts would be made to
minimize these exceptions.

Additional goals:

   - Separate requirements for valid IDNs at registration time
     (insertion of names into DNS zone files), vs. at resolution
	time (looking up those names)

   - Review, and, as necessary revise, the algorithms and rules
     for handling right to left character sequences in an IDN
	context to allow labels based on additional scripts and
	languages and to make presentation as predictable as
	reasonably possible.

   - Permit effective use of some scripts that were
	inadvertently excluded by the original protocols.

   - Ensure practical stability of validity algorithms for

The constraints of the original IDN WG still apply to IDNABIS,
namely to avoid disturbing the current use and operation of the
domain name system, and for the DNS to continue to allow any
system to resolve any domain name in a consistent way. The
basic approach of the original IDN work will be maintained --
substantially new protocols or mechanisms are not in scope.  In
particular, IDNs continue to use the "xn--" prefix and the same
ASCII-compatible encoding, and the bidirectional algorithm
follows the same basic design.

The work is initially organized as four documents: overview and
rationale, protocol, table algorithm, and changes to the
bidirectional algorithm. These documents are to be used as the basis
for the discussion of the general direction of the work.

This working group will be providing extended public review of
the output of a design team that has been working on the issues
described below. This review-based approach is being used in
part because of the way the work was undertaken by the team; in
particular, the design team has been working with IETF
visibility and has solicited and received significant amounts
of technical review already.  If the public review provided by
this Working Group confirms the basic method outlined in the
input documents, it is expected that the working group will be
able to provide any needed changes and close in a short period
of time.  If technical issues arise that indicate a
fundamentally different approach must be taken, it is
anticipated that this working group would close, and a new one
with an appropriate charter would be considered.

This work will address stable and unambiguous IDN identifiers.
There are a variety of unsolvable problems, notably the problem
of characters that are confusingly similar in appearance (often
known as the "phishing" problem) that are not part of the scope
of the WG.

While it is referenced from the original IDNA package, the
original Stringprep specification, RFC 3454, is not formally
part of the IDNA package and will not be altered by this work.
The work will update or obsolete RFC 3490.  It is not expected
to continue to use Nameprep (RFC 3491).  Nameprep is used by
other specifications; determining how (or whether) to update
those specifications and, consequently, the long-term status of
Nameprep, are not part of this effort.  The method for
ASCII-compatible ("ACE") encoding of IDNs, "Punycode" (RFC
3492) will not be revised by this WG.

Subject to the more general constraints described above, the WG
is permitted to consider changes that are not strictly
backwards-compatible.  For any such change that is recommended, it
is expected to document the reasons for the change, the
characters affected, and possible transition strategies.

The assumptions outlined above are considered critical to the
WG constituted this charter.  The WG will stop, close, and
recommend that a new charter be generated if it concludes that
any of the following are necessary to meet its goals:

    (i) A change to the "punycode" algorithm or to the ACE
    approach to encoding names in the DNS.

    (ii) A change to the ACE prefix from "xn--"

    (iii) A change to the basic approach taken in the design
    team documents (Namely: a protocol that is independent of Unicode
    versions, that removes any character mapping in the
    protocol, and that has improvements to the bidi algorithm).

Goals and milestones:

Apr 08: WG formation
May 08: Decision on form and structure of the WG document set
Sep 08: WG Last Call on WG document set
Nov 08: IETF Last Call on WG document set



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